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Sebastian St. Cyr #16

What the Devil Knows

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Sebastian St. Cyr thought a notorious killer had been brought to justice until a shocking series of gruesome new murders stuns the city in this thrilling historical mystery from the  USA Today  bestselling author of  Who Speaks for the Damned .

It's October 1814. The war with France is finally over and Europe's diplomats are convening in Vienna for a conference that will put their world back together. With peace finally at hand, London suddenly finds itself in the grip of a series of heinous murders eerily similar to the Ratcliffe Highway murders of three years before. 

In 1811, two entire families were viciously murdered in their homes. A suspect--a young seaman named John Williams--was arrested. But before he could be brought to trial, Williams hanged himself in his cell. The murders ceased, and London slowly began to breathe easier. But when the lead investigator, Sir Edwin Pym, is killed in the same brutal way three years later and others possibly connected to the original case meet violent ends, the city is paralyzed with terror once more. 

Was the wrong man arrested for the murders? Bow Street magistrate Sir Henry Lovejoy turns to his friend Sebastian St. Cyr, Viscount Devlin, for assistance. Pym's colleagues are convinced his manner of death is a coincidence, but Sebastian has his doubts. The more he looks into the three-year-old murders, the more certain he becomes that the hapless John Williams was not the real killer. Which begs the question--who was and why are they dead set on killing again?

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First published April 6, 2021

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About the author

C.S. Harris

23 books3,018 followers
Candice Proctor, aka C.S. Harris and C.S. Graham, is the bestselling, award-winning author of more than a dozen novels including the Sebastian St. Cyr Regency mystery series written under the name C.S. Harris, the new C.S. Graham thriller series co-written with Steven Harris, and seven historical romances. She is also the author of a nonfiction historical study of the French Revolution. Her books are available worldwide and have been translated into over twenty different languages.

Candice graduated Phi Beta Kappa, summa cum laude with a degree in Classics before going on to earn an MA and Ph.D. in history. A former academic, she has taught at the University of Idaho and Midwestern State University in Texas. She also worked as an archaeologist on a variety of sites including a Hudson's Bay Company Fort in San Juan Island, a Cherokee village in Tennessee, a prehistoric kill site in Victoria, Australia, and a Roman cemetery and medieval manor house in Winchester, England. Most recently, she spent many years as a partner in an international business consulting firm.

The daughter of a career Air Force officer and university professor, Proctor loves to travel and has spent much of her life abroad. She has lived in Spain, Greece, England, France, Jordan, and Australia. She now makes her home in New Orleans, Louisiana, with her husband, retired Army officer Steve Harris, her two daughters, and an ever-expanding number of cats.

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5 stars
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Displaying 1 - 30 of 539 reviews
Profile Image for Thomas.
1,016 reviews264 followers
March 7, 2021
4 stars for a page turner book set in Regency England. It opens in 1814 London, when Sebastian St Cyr, Viscount Devlin and son/heir of the Earl of Hendon, is called to the scene of a gruesome murder. An Est End magistrate, Sir Edwin Pym has been found with his throat cut and his head bashed in. This murder is reminiscent of the Ratcliffe murders 3 years before. Sir Henry Lovejoy, a Bow Street magistrate, frequently calls upon Devlin for assistance in solving murders. Devlin is a wealthy man through his father and assists Lovejoy without pay.
Devlin can ask questions where Lovejoy cannot, because of his position. Devlin begins investigating and slowly uncovers more murders connected to this and the Ratcliffe murders. There are powerful people who don't want the truth to come out. Devlin is attacked 3 different times, a recurring theme in this series. He escapes with only bruises and cuts. The book reads well. The plot unfolds briskly and the characters are believable.
Concerning titles, the English love of titles has produced some interesting responses in the US. In the 60s, there was a popular song "The Duke of Earl." Five years ago, when my grandson was 8, he told his mom, that he was "Sir Patrick, Duke of Awesomeness."
The author is very accurate in describing the clothing and speech of the time.
Two quotes:
Devlin's wife: "Hero Devlin sat in one of the upholstered chairs beside the drawing room fire. Dressed in a long-sleeved afternoon gown of soft midnight blue wool made high at the neck and embellished with champagne-colored rosettes, she had a serviceable notebook balanced on one knee while her young son played on the hearthrug nearby."
Description of a wealthy brewer: "In his midforties, Buxton-Collins was a mountain of a man with a head of curly fair hair, a strong nose and chin, and the cold, alert eyes of a raptor. Despite his size, he had a reputation as an avid sportsman and something of a dandy. He was dressed in yellow pantaloons, glossy black boots, a double-breasted navy blue coat, and an elaborately tied cravat with a jeweled quizzing glass hanging from a silk riband around his neck."
This is book 16 in the series, and I recommend that you read them in order. Book 1 in the series is What Angels Fear My review https://www.goodreads.com/review/show...
Thanks to Berkley for sending me this eARC through Edelweiss.
Profile Image for Julie .
4,251 reviews38k followers
July 3, 2021
What the Devil Knows by C.S. Harris is a 2021 Berkley publication.

When a magistrate and a seaman are both murdered in a similar fashion, using the same modus operandi as the Ratcliffe Highway Murders, three years prior, Sebastian is asked to aid in the investigation. The case is especially tricky as The Highway murderer was presumably caught- but committed suicide. It then stands to reason that this present- day killer couldn’t be the same person- right?

What connection does a magistrate, a seaman, and the violent murders of two families have in common? Sebastian soon begins to uncover a web of corruption designed to protect the hierarchy and continue to greedily line the pockets of the affluent…

This installment in the long-running series is very complex! It’s a smart, carefully crafted plot and commanded my undivided attention. As always, the vivid descriptions help to create the palpable atmosphere that makes this series so effective. I’m also on pins and needles about the developments with Hero’s father and the news concerning Sebastian’s mother.

The mystery was one of the better ones in the series- the intrigue, social commentary, and the fabulous characterization keep this series at the top of my favorites list!

4.5 stars
December 9, 2021
“The only reason any of this happened is because our society is so bloody corrupt” add to that the exposure of an inadequate and crooked law enforcement system prompting the creation of a national police force in Britain and the work of what looked like a serial killer, and you get an amazing historical crime thriller set in Regency Britain in the early 1800’s, inspired by true events.

The Ratcliffe Highway Murders of 1811 shocked London to its core because the brutality was on a scale never seen before and involved the gruesome murders of two entire families. Most of the bodies were displayed to create the theatre, instil fear and as a warning to the brave or foolish people who threatened to unsettle the status quo of the money makers and magistrates who protected them. There was a palpable aura of horror that hung over London which was only to be repeated by Jack the Ripper decades later in an area not far from Cable Street and the London docks.

The cases from 1811 were seemingly closed when the murderer, of the four people at Marrs’ shop, three at the Kings arms, had committed suicide and when the body of John Williams was paraded through the streets and a stake driven through his heart, only then did London relax from the fear of a grisly blood-spattered death. Yet no one made the connection to the deaths of men tangentially linked to the Ratcliffe murders who continued to die under suspicious circumstances. That is until Viscount Sebastian made the link forcing him to investigate the deaths of more victims and a possible copycat murderer or accept the possibility that the wrong man was accused driving him to an apparent suicide.

Once again, the air was rife with suspicion and fear but few answers as Sebastian’s investigation takes him into the back streets and working-class taverns in East London, and to the dirty politicians and clergy who thought only of lining their pockets rather than seek justice.

The setting was wonderfully atmospheric, the historical detail of the regency period was superb and whilst a fictional novel, the book is ominously close in accuracy to the real events of 1811. The writing made this book such an immersive read, however if there was one criticism it would be that some of the detail was repetitive. The author tended to recount the same details of the murders in a few different conversations throughout the book which was unnecessary. Nevertheless I would recommend, a great read otherwise.
Profile Image for Diane S ☔.
4,901 reviews14.6k followers
April 18, 2021
When you're reading a good series, a series that retains its high standards, one is surprised to find that this is book number 16. How the years and books fly by. This book follows Lord Devlin, Sebastian St. Cyr as he attempts to solve a case that eventually reason includes a great many bodies. It also mimics murders from three years previous, where it was thought the killer had been brought to justice, though he killed himself before he could be convicted. His wife Hero is still compiling knowledge for her series on women on the street and she will use this endeavor to aid her husband.

I love this series, though I admit there were so many publicans, different characters that in the beginning this was confusing. As I read the main characters became clearer, and I sank into the mystery of who was doing what, and of course, why. That in the authors note at books end I find that these cases were real cases in history, was a bonus. I enjoy these characters and the book does draw one into the time period, that of the early 1800s. At books end Sebastian decries the seemingly unending corruption of those of higher status. Graft and corruption, sometimes it seems that we have not come very far as a society but are doomed to repeat history, over and over again. Greed and the perfidy of man..

ARC from Edelweiss.
Profile Image for Phrynne.
4,038 reviews2,736 followers
April 26, 2021
Sebastian St Cyr is back in his sixteenth outing, still trying to solve crimes in the lawless streets of old London. Always helping him, and occasionally saving his life, is his much loved wife, Hero.

These are absolutely splendid books. They tell it as it was in London at that time and many of the stories and characters are based in fact. The author summarises at the end which bits were fiction and which were not.

The author writes her characters so well and I have loved the relationship between Sebastian and Hero since it began. They now have such a comfortable marriage with a small son, a parrot (a Galah no less) and a whole bunch of servants. A couple of interesting possible future events mean I am already looking forward to the next book
Profile Image for Mei.
1,897 reviews472 followers
April 9, 2021
It pains me to admit that I didn't like this one as much as the previous books in this series... :(

Most of the time I was confused about who was who and what does him or her have to do with anything!

It was all too complicated to follow...

Also there was not enough interaction with all the secondaryy characters... Lovejoy, Jarvis, Victoria, etc... they were just mentioned in passing!
Mostly it was Sebastian interviewing different people asking questions that didn't make anything clearer than it was before those questions were asked! He was running here and there, but without actually getting anything!

Then the ending come out of nowhere and it just ended...just like that!

So, I'm sorry to say that for me this was not more than meager 3 stars and only because the writing and descriptions were good, not because of the story...

I really, really hope the next book will be better! I would hate for this series to slip into mediocre...
Profile Image for Carolyn.
2,759 reviews753 followers
April 14, 2021
I love this series for the mix of clever crime, smart and interesting characters and the smells and sights of Regency London so well depicted amongst the pages. In this sixteenth volume of the series, C. S. Harris has brought us a complex and curly plot based on the actual murder of two families in 1811, known as the Ratcliffe Highway murders. Altogether seven people, including a baby, were found dead in their homes, with their heads bashed in and their throats cut.

Lord Devlin, Sebastian St Cyr, often called in to help the London police with their enquiries, particularly when the powerful and wealthy are involved, recalls the Ratcliffe Highway murders well. Especially when now, three years later, two bodies, that of a magistrate and a seaman were found in the streets near the London docks, killed in the same way. While a man was arrested for the Ratcliffe Highway murders, some felt he might not have been guilty. However after he died, no more murders were committed until now, but Sebastian can't help feeling that there must be links between the older murders and the recent ones.

This was quite a complex plot involving corrupt magistrates, brewers, publicans and seamen in the docks area of London's east end. There were a lot more murders before the end of the book and I have to admit to having trouble keeping track of all the different public houses Sebastian was visiting and the number of different people he was talking to. However, eventually the crime does come into focus and it all makes sense.

Because the novel was so plot driven, there seemed to be less involvement of the other characters in the series in this novel, with most having cameo roles at best. Most of the sleuthing is carried out by Sebastian, with little opportunity for Sir Henry Lovejoy's Bow St police or Sebastian's tiger Tom to be involved. This was a shame, as Sebastian's family and friends are an important element of what makes this series so enjoyable. Sebastian is also no further along with the search for his mother, but a possible family connection resurfaces in this novel, which will be important to Sebastian in the future. 4.5★
Profile Image for ScrappyMags.
625 reviews387 followers
April 19, 2021
Before the Holmies...

Shortest Summary Ever: London, 1814. Before Scotland Yard where local boroughs rule themselves and corruption controls the day, Viscount Sebastian St. Cyr is brought in to investigate a series of gruesome murders, eerily similar to those from three years ago. Except the man accused of doing that is dead, and Cyr believes him not guilty. So who is behind the sinister murders and why are they beginning again?

Thoughts: Straight up Sherlock. If you enjoy Holmes, you’ll likely enjoy this. Based on true events and accurate history, the author brilliantly weaves fiction into true and gruesome details, and that’s why I’m stan for historical fiction mysteries - the vivid pictures that played in my head were better than anything on tv (yes, even you Bridgerton!).

This is book 16 in a series, but my first and it was easy to jump in (and yes, I’m going back now to read the first ones!). So many characters, red herrings, plaited bands of who-dun-its make for a wonderful weekend read.

All my reviews available at scrappymags.com around time of publication.

Genre: Historical Fiction Mystery

Recommend to: all the “Holmies” - very similar to Doyle. Historical fiction mystery fans like me will swoon.

Not recommended to: If you’re not into a period mystery.

Thank you to the author, NetGalley and Berkeley Publishing Group for my advanced copy in exchange for my always-honest review and for keeping me awake!
Profile Image for Jonetta.
2,599 reviews1,331 followers
April 6, 2021
In 1811, two families in the Wapping area of London were viciously and brutally murdered, including an infant boy. The case became known as the Ratcliffe Highway murders and the man arrested as a suspect hanged himself before he even had a hearing. Since the murders ceased, all of London believed the suicide suspect to have been the rightful killer. However, three years later, a magistrate in the same area and a seaman were murdered in the same way as the victims in the Ratcliffe Highway murders. Sebastian St. Cyr is asked to help investigate by Sir Henry Lovejoy, one of the London Bow Street magistrates and a close friend. The more Sebastian probes, the more he’s at risk and even he can’t ignore that the murders are probably connected.

This story took some time to develop because in order to make sense of the current murders, the events from three years ago required deeper analysis. It has so many angles and seedy characters that it was often difficult to find clarity. I’m used to Sebastian finding corrupt government officials with a hand in the case to some degree but the depth and breadth of this one was difficult to absorb. Even I wanted him to walk away from this one.

Sebastian’s wife, Hero, also plays a substantive role here, too, as she continues her research into the plight of the impoverished of the city and government’s role in putting and keeping them there. But this time danger reaches their doorstep, which added a truly sinister element to the story. Of course, father-in-law Jarvis is also in the mix and there are surprises there, too. I enjoyed the story, especially since the Ratcliffe Highway murders of 1811 was a true event on which this is based. The true crime element made this a more interesting reading experience. Still loving this extraordinary series.

Posted on Blue Mood Café

(Thanks to NetGalley and the publisher for my complimentary copy. All opinions are my own.)
Profile Image for PattyMacDotComma.
1,778 reviews1,059 followers
November 26, 2025
4★
" 'I came here for one reason and one reason only,' said Sebastian, stopping him. 'And that’s to tell you this: Send someone at me again and you’ll regret it.'

'You can’t just throw something like that in a man’s face and leave,'
sputtered Buxton-Collins as Sebastian turned to go.

But Sebastian kept going, the elegantly dressed, overfed crowd parting before him like a school of fish clearing the way for a dark predator."


I always enjoy visiting the terrible back streets of Regency London with Sebastian St Cyr (Viscount Devlin). I am happy to suspend disbelief that he can single-handedly dispatch three assailants in the dark, go home, battered and bloody, where his gentleman's gentleman, Jules Calhoun's "unflappable disposition and unsurpassed skills with brush, needle, and iron made him invaluable to a nobleman whose pursuit of murderers could at times wreak havoc on his wardrobe. "

Note that's a brush, not a washing or cleaning fluid. Wife Hero will patch the cuts, Calhoun will find fresh clothes, and Sebastian will be fine by morning to dive back into the fray. As I say, I won't pick bones about his amazingly quick recoveries.

But this book didn't appeal to me as much as the previous stories, and I suspect it's because it was a complicated plot with a lot of characters and barely a passing mention of what's happening with all the familiar people we've been following for a long time.

Hero thinks of some as she looks at their little boy, Simon.

"Hero found herself wondering just how much of each of his four very different grandparents swirled around within this little boy: Jarvis, so brilliant, hard, and merciless; the scandalous Lady Hendon, so beautiful and so outrageous; Hero’s own gentle mother, dead now for over a year; and that other grandfather, the shadowy figure who remained a mystery to them all. The man who had fathered Devlin on another man’s wife before disappearing without a trace."

But the atmosphere and setting are as wonderfully awful as ever.

"Molly Maguire hated the fog. Hated the way it reeked of coal smoke and tore at her throat. Hated the way the damp, suffocating blanket could turn even the most familiar lane into something ghostly and strange."

The story opens with Molly, a tiny, underage prostitute in an alley, 'servicing' a fat old man who refuses to pay and leaves, because why not? She sees the night watchman, so ducks into another alley to hide. Eventually she thinks she's safe to leave.

"She had her head turned, looking anxiously over her shoulder for the watchman, when her foot caught on something and she pitched forward.

'Mother Mary and all the saints,' she swore softly as she came down on what felt like a big overstuffed sack. Her outflung hands slid over warm, smooth cloth and something else. Something wet and sticky.

Rearing back with a gasp, she stared down at the man before her, at the familiar greatcoat with silver buttons, at the hideous yawning wound in that fat neck, at the fine once-white cravat now soaked dark with blood. More blood matted his bushy gray hair and swooping side-whiskers."


Her disgusting client is the first of the countless bodies in this St Cyr episode, and I was pleased to see him go. But soon there are other murders reported that are reminiscent of a spate of murders thirty years ago, slaughters of families for no apparent reason. The supposed culprit hanged himself in prison, also supposedly. Nobody followed up because the public had been terrified of a random killer at large, and now they felt safe.

When something similar happens today, 1814, Sir Henry Lovejoy, a stipendiary magistrate from Bow Street, asks Sebastian, who has helped him before, to assist in the investigation. The public is getting wary again, and as it looks like there may be a connection to publicans, Sebastian turns to Calhoun, who was raised in pubs and whose mother still runs one. She knows everybody we wouldn't want to know.

The extensive author's note at the end explains the history behind this fictionalised real story, and I probably would have appreciated it more had I known. As it was, I began thinking I needed a flow chart or one of those big whiteboards detectives on TV shows stand in front of, drawing lines between pictures and moving pins on maps.

I do enjoy seeing how the pair of Sebastian and Hero (with help from Calhoun this time), use their various skills and contacts to gather pieces of information to put together. Of course they figure it out, but we are still left hanging about the rest of their family – with one new exception, something of a cliff-hanger that will keep us coming back for more.

This is still first-rate historical fiction that usually has more family and friend threads tying things together, but it's not a soap opera and I like the history. I’m looking forward to the next one.
Profile Image for Montzalee Wittmann.
5,224 reviews2,340 followers
February 8, 2021
What the Devil Knows
by C.S. Harris
Berkley Publishing Group
I want to thank the publisher and NetGalley for letting me read this book!
This is the first book in the series I have read and it didn't bother me, or make me feel lost in the story regardless that this is book #16. It will certainly not be the last book in the series now that I know how wonderfully exciting and intriguing they are!
This mystery book is set in the early 1800's and the dialogue and world building really makes you feel like you are in England at that time. Much of the story is historically correct. In the end of the book, the author lets the reader know which parts are taken from historic events and which are added. That makes the story all the more fun!
All though the mystery is about a gruesome murder, which is true to history, there are so many layers to the mystery and solving the crimes. Yes, crimes, with a S. So much happens in here it really kept me turning the page and keeping my thinking cap on.
Although there were a lot of characters in here, the way the author presented them there was no way I could forget them, and there were many, many people! Well developed characters and all very unique.
It was a sad story of death, corruption, of society at that time which preyed on the poor and women. But I guess some things never change in human nature. We still have that today.
I ordered more of Harris' books from the library and can't wait to get them! I highly recommend this exciting and intriguing mystery book! Many layered crimes, mysteries, and it's very informative too!
Profile Image for Ira.
1,157 reviews130 followers
April 24, 2021
4.5 stars.

What to write?
Plenty review about this book already and I am a big fan of Sebastian and Hero, so my review probably a little bit bias?

Anyway these are my random thoughts. ☺️.
I know early on the killing sounds like a revenge, but based by informations we’ve got from Sebastian’s, I couldn’t guess by who, how and why either. So yes, I got the answer at the same time with Sebastian and how heartbreaking that was 🥺.

If there is something I want to complaint about this series, is the whole series always feels doom and gloom. While I love the story of Sebastian’s and Hero’s relationship and they are getting better and wonderful, the rest of the story always full with heartbreaking situation 🥺.

I feel like I’ve got all my yearly ‘angst quota’ by reading this series once a year! 🥺🥴

I don’t know what to say, it would be a perfect read if Ms Harris would give us an uplifting feel by the end of the story and made us a bit positive about something, but it wasn't happening, yet 😩.

Like this one, even those few pages at the end of this book is heartbreaking, my god what kind of woman to do that? She deserved that awful guy and Sebastian can pay something back to J. 🥺.

I can’t wait to see this new character as a part of St. Cyr family 😍🥰.

❤️
Profile Image for h o l l i s .
2,735 reviews2,309 followers
April 9, 2021
I'm rather tempted to round up on this one, at which point this intro will be deleted, but for now (or for good), I am a little hesitant. I don't know if I'm thinking more fondly of this experience because it's been a year since the last installment, around the same time I binged like.. fourteen of these back to back (which was just too much), or because it was just a little better than the last few.

We had a few moments of what I refer to as "copy paste" scenes which Harris seems to include in all her books but overall, much like the last book, there were quite a few less than usual. I was delighted.

The murder mystery itself was.. kind of all over the place. In the sense that there were so many pieces and moving parts and you really don't see the big picture until the end. I both love and hate these kind of mysteries because I find the complexity very artful but it also means that if you aren't being compelled by the new clues, you're just sorta being dragged along. Which wasn't quite the case here but it was close.

What saved said mystery from feeling too out of place from too many pieces of the puzzle were some familiar, and new, faces that tie into Sebastian's personal life. I was curious why we were reunited with a few of them but oh you understand why come the end. I can't say I totally saw that coming but neither was it a complete surprise. There was another event that finally came to pass that I think means we might finally be building up to something else (why am I even expanding on these vagueries..) that has been brewing for, I swear, like four or five books now. When is that confrontation going to happen! Will it ever! Why do I ask the same rhetorical questions in every review for this series! I'm not mad I'm just making a point about my own ridiculousness.

Much like some other series I'm keeping up with, I wonder how many more are still to come in the Sebastian St Cyr series. However unlike those other series, I'm not currently mad about this one.. well, continuing on. Despite some of the rehashing and a new murder mystery of the week duds, somehow, I'm still looking forward to more. Maybe because I just want to payoff of everything that we've come to expect will (one day) be revealed. Any hints on when that might be, Harris..? No? Cool. Cool cool cool cool cool. See you next year.

3.5 stars

** I received an ARC from NetGalley and the publisher (thank you!) in exchange for an honest review. **

----

This review can also be found at A Take From Two Cities.
Profile Image for Victoria.
39 reviews2,260 followers
Read
February 28, 2023
A series that keeps getting better.

Another thrilling adventure for Lord Declin and his wife as they try to find justice in an unjust world.You'll love it.
Profile Image for Caz.
3,273 reviews1,179 followers
May 9, 2021
I've given this a B+ at AAR, so 4.5 stars

This sixteenth book in C.S Harris’ series of historical mysteries featuring aristocratic sleuth Sebastian St. Cyr is an entertaining page-turner which sees Sebastian investigating a number of particularly gruesome murders in and around London’s East End. As always with these books, the historical background is fascinating and incredibly well researched (it’s always worth reading the Author’s Note at the end; not only will you learn new things, you’ll learn just how skilfully Ms. Harris incorporates actual historical events into her stories), and the mystery is well-paced, with plenty of twists, turns and red herrings.

At the beginning of What the Devil Knows, Sebastian is called in by his friend, Bow Street magistrate Sir Henry Lovejoy, to help investigate the murder of Shadwell magistrate, Sir Edwin Pym, whose body was found in a dank alleyway in Wapping with his head smashed in and his throat slit from ear to ear. Sebastian and Lovejoy are immediately reminded of the brutal slayings, three years earlier, of two families known as the Ratcliffe Highway Murders. A linen draper and a publican were the seemingly unconnected victims and although a man was arrested for the crime, he was found hanged in his prison cell the day before his trial and the investigation was closed. There were whispers at the time that the magistrates – of whom Pym was one – were too eager to blame a conveniently dead man, but the murders ceased and eventually, the gossip died down. But Pym and another man – a seaman named Hugo Reeves – who was murdered some ten days earlier, were killed in exactly the same way as the Ratcliffe Highway victims – and Sebastian and Lovejoy can’t help but wonder if they are the work of the copyist or an accomplice… or if they’re the work of the person responsible for the earlier murders, who managed to escape justice three years earlier.

After making a few inquiries and observations of his own, it doesn’t take long for Sebastian to become fairly sure that John Williams, the supposed culprit who hanged himself, was not only not guilty of the original murders, but that he was framed for them, and when another magistrate – Nathan Cockerwell from Middlesex – is found dead just days later, his head bashed in and his throat slit, Sebastian is more sure than ever that the two sets of murders are somehow connected. Discovering that both Pym and Cockerwell were part of an alliance between corrupt government officials and some of the city’s richest, most powerful brewers, who forced public houses to purchase their beer and spirits from them and would put them out of business if they refused, Sebastian slowly starts to piece together a bigger picture and to draw together the links between the three-year-old murders and the more recent deaths of Reeves, Pym and Cockerwell.

The story that follows is fast-moving and satisfyingly complex, as Sebastian moves from suspect to suspect, many of whom have much to hide and are rarely forthcoming. As always, the author skilfully incorporates some of the lesser-known histories of London into her plot, and the way Sebastian pieces together all the snippets of information – and weeds out the lies he’s fed along the way – is superbly done, with lots of character interaction, investigative pondering and insightful observation about the huge disparity that existed between the haves and have-nots, and the injustices perpetrated on the lower echelons of society by greedy public officials and institutions that were supposed to exist for the betterment of all, not just a self-serving few.

Sebastian continues to be a compelling, sympathetic character, and one of the things I so enjoy about this series is watching him grow and change from the hot-headed younger man who was careless of his own safety to a devoted husband and father, a truly and deeply compassionate man who believes strongly in justice and in using his position and abilities to speak for those who are unable to speak for themselves. His wife, Hero – daughter of the devious, formidable Lord Jarvis – shares his interests and convictions; she is an investigative journalist who writes about what life is really like for London’s poor and less fortunate, and I love how in-tune they are and the way they are each other’s staunch support. She has a relatively small part to play in this story, but her discoveries pack a considerable emotional punch as she interacts with young women making a living on the streets, telling stories about their lives and experiences that are far from pretty.

As with the last few books in the series, the standalone mystery takes precedence, so a reader new to it could jump in here and not feel as though they’re missing anything. This has been the case with the last couple of books; the long-running storylines concerning Sebastian’s search for the truth about his heritage – and particularly his search for his mother – his relationship with his father, and the machinations of the Machiavellian Lord Jarvis are present, but are simmering along on the back-burner. Sebastian learns that his mother has been living in Paris, but that she’s recently removed to Vienna – where European heads of state are gathering to put “the world back together after the defeat of that Corsican upstart” – under an assumed name, but has no idea why; Jarvis’ relationship with the cunning and mercenary Victoria Hart-Davis (were ever two villainous characters so well suited to each other?) progresses, and changes are afoot in Sebastian’s household. As the timeline of the series inches closer to Napoléon’s escape from Elba and to Waterloo, I become more and more intrigued as to what lies in store for Sebastian – and I certainly plan on sticking around to find out.

What the Devil Knows is another strong instalment in the Sebastian St. Cyr series. The mystery is gripping and tightly-written and the author’s descriptive prose is – as always – so wonderfully evocative that the reader can feel the dampness of the creeping fog , see the crowded tap-rooms and hear the gulls screeching overhead around the docks. Why is it not a 5 star book? Simply because I’m starting to feel the need for a bit more movement on issues surrounding Sebastian’s history; this seems to have been pushed aside in the last few books in the series – and while I can sort of understand the author wishing to keep this particular mystery going a bit longer as she obviously has more stories to tell, cynical me can’t help but see the drawing out of it as a delaying tactic.

But don’t let that put you off; this series is one of the best (if not THE best) historical mystery series around, and What the Devil Knows is another fantastic read.
Profile Image for Daniel Shindler.
320 reviews210 followers
April 26, 2021
I always get a sense of delight when a new book arrives in this wonderful series. The books present a well thought out mystery and also immerse the reader in the society and politics of the fascinating Regency period. In this installment, the plot centers around an actual historical event, The Ratcliffe Highway murders. By all historical accounts, these murders aroused as much panic in London as those of Jack the Ripper eighty years later. Two families, including a little baby, were viciously murdered. A culprit was apprehended and he hanged himself in his cell.Many people familiar with the culprit were doubtful that he was the perpetrator.Nevertheless, the murders stopped and the city regained an aura of calm.C.S. Harris builds on this incident to posit a set of murders three years later that are reminiscent of the murders in 1811. Sebastian St Cyr is unsure if these murders are the work of a copycat killer or if they signal the reemergence of people associated with the original crimes. With the help of his wife Hero, Sebastian decides to find out.

The strength of this novel( and of the entire series) is contained in the characterization of the protagonists and the depiction of Regency England.Sebastian, formally Lord Devlin, is well suited for investigation. He was a former officer in the army, working in military intelligence.He has unusual physical gifts, being blessed with an acute sense of hearing and vision. He has yellow, almost lupine eyes which can intimidate with a well placed glare. In addition, he is their heir to his father Lord Herndon’s estate.Lord Herndon is the Chancellor of the Exchequer. Sebastian’s membership in the upper reaches of society give him access to homes unavailable to the law agencies in this highly stratified society. Sebastian’s wife Hero,ironically, is the daughter of Herndon’s biggest political rival, Lord Jarvis. He is the Machiavellian minister without portfolio who guides the weak Prince Regent in governing the realm.Hero is a woman with a highly developed social conscience and is often at odds with her father.Together Sebastian and Hero make a formidable team.

The mystery itself is complex and has many levels of intrigue . In pursuing this conundrum, Sebastian and Hero move through different layers of London society. They discover hints of collusion and corruption in the brewing industry and public houses, government attempts at suppression of working class rights and surreptitious spying on working class taverns, fearing them as a source of social discontent.

These components of the novel are seamlessly woven into a well thought out plot.Regency England marked the beginning of Britain’s consolidating its hegemony in Europe and beyond. The French Revolution had come to a close and the Napoleonic wars had just ended.The powers in England were wary of the egalitarian ideas in France spreading to its shores.Hints of this tension arise in this well thought out series.Part of the delight of this book is the sense of tension and political unrest conveyed in the protagonists’ dialogue.
This installment is more centered on plot and less on characterization than many of the previous books. No matter.The novel is still a heady mix that will engage and inform.
Profile Image for Blackjack.
484 reviews199 followers
March 4, 2021
Sebastian St. Cyr books are nearly always comfort reads for me now, and about this time of year, I start longing for a new one. Here is Book #16 of this long-running series and in most ways, it delivers. Harris delves into the true crime story of the Ratcliffe Highway murders and in doing so, examines the corrupt parish government extortion of local beer breweries and publicans. I enjoy learning new aspects of early 19th-century life and Harris is an expert at conveying the slighter known histories within an exciting fictional plot. Having said that, I found the mystery here a little underwhelming and even a little confusing at times. The murder victims are high in number and by the end of the who-done-it, I was confused and had trouble sorting out the players.

The book also features a couple of new additions to the cast, and a parrot! The entry of these characters could ultimately be crucial to new stories, though I felt their sudden insertion into the St. Cyr household a little abrupt and mystifying. I have no idea how important Molly will be or why she is a permanent cast member. Hero and Sebastian both routinely meet downtrodden people in the course of their adventures, and it's not always clear why some are elevated to permanency and others are left out in the dark. The other new character in this story though seems potentially very important, and I'm eager to see how Hero and Sebastian handle this new addition.

There is a trace of action on the Jarvis/Victoria front, but it's minuscule and left me feeling frustrated at the slow pace of development in the personal lives of the characters. Overall, not the strongest story of the bunch but still an entertaining edition to the St. Cyr canon.

Profile Image for Anita.
2,651 reviews219 followers
November 30, 2023
I have just one problem with the audio book version of these books: I can't keep track of all the characters. I much prefer to read them on my Kindle so I can use the X-Ray function to keep track of who is who. A lot of people in my area must feel the same way because the wait for the Kindle version is months long at my libraries. Davina Porter is a wonderful narrator, and she makes being lost in the character lists not feel so bad. I found it difficult to get into this one, I'm sure it was trying to do Black Friday shopping while listening in addition to the complicated mystery. I've decided to stick with Romance for my audio shopping excursions, they don't task my brain so much.
857 reviews4 followers
February 3, 2024
Book 16 of the Sebastian St Cyr Mysteries

Once again CS Harris uses her research skills to give a historic note to her very well done murder mystery. This time set three years after the Ratcliffe Highway murders of 1811, which play heavily into the new investigation. Corrupt magistrates strong arming in owners into buying from particular breweries Boston investigations the foundling hospital and the great beer flood of 1814 all play A part as Sebastian St Cyr tries to find who is killing the people behind the Ratcliffe Highway murders.

Another superbly done mystery and a good piece of Regency history.
Profile Image for Sharyn.
3,151 reviews24 followers
June 24, 2021
I can't believe this is #16 and still going strong!! Only about 3 years have passed, which I love as the books just follow one after the other. St. Cyr is called to help in yet another murder, which may be a copy of a real murder from 3 years before, or is it the same murderer and the wrong person was accused?? This book delves into the corruption that was rampant in London during the Regency. The Upper classes were so afraid of a revolution like France, that they managed to keep the lower classes down even more ruthlessly. St.Cyr's wife Hero is a wonderful character who writes articles about the poor, and feels hopeless in the face of poverty. She tries to save some, and is just appalled by how little people care. There are still mysteries to be solved and I do hope one day we meet St. Cyr's mother and discover who his father is and how that will affect him
There is a very sad ending that might bring hope to a little boy. Will be eagerly awaiting the next book.
Profile Image for Barbara Rogers.
1,754 reviews208 followers
March 23, 2021
Series: Sebastian St. Cyr #16
Publication Date: 4/6/21
Number of Pages: 336

Long before Victorian London had Jack the Ripper, Regency London had the Ratcliffe Highway murders. Two families, seven people including a 3-month-old baby were brutally murdered. The culprit was caught and he hung himself in his jail cell. Three years later there is another murder that is the same as those from Ratcliffe Highway – and then another, and then another. Did they get the wrong murderer three years ago? Did that murderer have a partner who is now killing again? Is it a copyist who is doing the murders? Sebastian has a very dangerous task ahead of him, but he must sort out all of the players and their various roles from three-years ago and now.

When the body of Sir Edward Pym is found in a filthy alley where his throat had been cut and his head bashed in, Sir Henry Lovejoy, a Bow Street Magistrate, immediately seeks the aid of his friend Sebastian St. Cyr, Viscount Devlin. Edward Pym was one of the magistrates responsible for the solution to the Ratcliffe Highway murders. As Devlin investigates, he discovers that there was another recent murder that was committed in the same manner. Devlin is pretty sure that the current murders are related to those of three-years ago – and after Mr. Nathan Cockerwell, another magistrate, is found murdered in the same manner, Devlin is positive they have to be connected.

There are many factions at work and some very powerful people want things their own way. Are they involved in both sets of crimes? With so many undercurrents and factions involved, it is like a bowl of spaghetti for Devlin to unravel. So many innocent victims – so many guilty victims – what a tangled web.

Many other things are going on in Devlin’s life as well – some are tangentially related to the case and some are not. Devlin gets some new information on his missing mother’s whereabouts; Hero and Simon are in danger when someone breaks into their home; Jarvis makes a huge announcement; There is a new addition (or two) to the St. Cyr family. I’m very curious to see what is going to happen with Mrs. Victoria Hart-Davis and I wonder if Jarvis will survive it.

This is a really exciting read and I couldn’t put it down. The writing, as always was excellently done, the pacing was perfect and the mystery was riveting. Just when you think you are sure you know what happened – a new fact drops in your lap or the investigation heads off in a different direction.

I definitely recommend this book – and this series – and I hope you will enjoy it as much as I did.

I voluntarily read and reviewed an Advanced Reader Copy of this book. All thoughts and opinions are my own.
Profile Image for CYIReadBooks (Claire).
846 reviews121 followers
March 24, 2021
Sebastian St. Cyr is a nobleman turned investigator. He is called upon by his friend to investigate a brutal murder that has all the makings of earlier crimes that occurred three years before. What was thought to be a closed case turns out to be otherwise. That perhaps an innocent man went to prison for crimes that he didn’t commit. Was he framed? And to what extent did government corruption play a role?

Crafted in the same vein as Sherlock Holmes, What the Devil Knows is a classic whodunnit where the reader joins Sebastian in the investigation process — interviews with witnesses, crime scene investigations, and attending autopsy examinations. It is a solid read with a well developed plot that the reader can follow and gather clues.

What the Devil Knows was an enjoyable novel. However, I felt as though there was a slight language barrier. Old English terminology coupled with the vernacular of that period tested my enjoyment. And being that this novel is the 16th installment, a new reader like myself may find the character development lacking. But, that lack of development could be attributed to the fact that the main characters have already been established in the earlier novels.

Overall, What the Devil Knows was a satisfying novel and a good fit for fans of historical fiction mixed with mystery. I’ve rated it three likable stars.

I received a digital ARC from Berkley Publishing Group through NetGalley. The review herein is completely my own and contains my honest thoughts and opinions.

Profile Image for Merry.
886 reviews288 followers
April 30, 2022
I have listened to all the books in the series in order. Davina Porter is as always, a delight to listen to...it is just the story and clues are not advancing the character part of the storyline. A few bits of action then just asking questions then repeat. I would like more of the storyline of the family and side characters to also move along. I found few lines of questioning that would have in anyway have led to figuring out the guilty party. It was overlong without moving the story. I see that the next book is not read by Davina Porter. I have it preordered and am waiting as it has been delayed.
Profile Image for Barb in Maryland.
2,098 reviews176 followers
April 20, 2021
4.5 stars

After the heartbreak of the previous book, Who Speaks for the Damned, I was glad that this book started with the murder of a Very Nasty Person.
It's October 1814: Sir Henry Lovejoy, Bow Street magistrate, wants Devlin's aid in investigating the murder of Sir Edwin Pym. It seems that Pym was killed in such a way as to bring the Ratcliffe Highway murders of 1811 back into the public's attention.
The 1811 case was wrapped up when the principal suspect hung himself right before his trial. The murders stopped; everyone breathed a sigh of relief. Now the fears start again--is this the 'real' murderer back in action, or a copycat, or someone trying to send a message?
I really enjoyed the way the author worked a well-known crime (the Ratcliffe Highway murders) into her story. I was sucked into Devlin's investigation of the older crime as part of trying to solve his current case. The author weaves the two cases together very skillfully, but the big picture is quite complex. I was quite thankful for Devlin's list of the various victims towards the end. I confess to reading the end chapters several times to make sure I was straight on who killed whom and why!
There are light domestic touches between all the murders. A new critter is introduced into the household, to Devlin's great amusement; young Simon is developing apace.
The book ends with an event that will definitely shake up Devlin and Hero's lives. Rats! Now I have to wait another year to find out how that will play out.

Profile Image for Kerry.
1,061 reviews182 followers
June 4, 2021
3.5 rounded up. I love this series but as it goes on I find C.S. Harris taking on more complex incidents and difficult mysteries that are based on real historical events of the early 1800's in London. I always listen to this series as it is narrated by Davina Porter whose voice and reading I love. The problem I had with this particular story was the number of names, the pile up of bodies and my ability to keep with the the thread of Sebastian's investigation as the events grew more and more difficult to follow as the characters flitted in and out of scenes. I loved that I could not see how or who was to blame for the killings happening and was lead down several blind alleys but I also got lost several times as to who was giving information and what it had to do with the current story. I think this might be a book better read than listened to, despite the wonderful narration. I went over several parts again but still could not always keep characters straight.
The historical notes at the end always add to the appreciation of the story and the author's true talent at weaving historical events into a wonderful fictional narrative. The pacing was great and the addition of new developments to the lives of Hero and Devlin will keep me enthralled with this series.
In all I regret I could not give it my usual 5 star rating as I felt the author did take on a little more than could be easily followed and enjoyed. Will be waiting for the next in the series. May go back and give this another listen.
Profile Image for Cortney -  Bookworm & Vine.
1,085 reviews258 followers
February 17, 2023
16 books into the series, and I'm still enjoying it!

I missed some of our regular characters this time though. While they were in it briefly, there wasn't enough of them! In return, we got what felt like too many new characters to keep track of while Devlin figured out the murders.

Looking forward to the next one!
Profile Image for eyes.2c.
3,114 reviews111 followers
April 3, 2021
Regency crime and more!

The massacre of a family, the untimely suicide of the main suspect, the death of a despicable magistrate, mutineers, blatant corruption concerning licences and taxes for pubs in the East End. The pressure by Breweries for publicans to only buy from certain breweries under threat of harm to them or their loved ones. There’s a veritable plague of disorder. Viscount Sebastian St. Cyr is tasked to assist and as his investigation moves forward greed, graft and extortion are a stench in his nostrils. The Home Secretary, Henry Addington, Viscount Sidmouth, has asked Sir Henry Lovejoy, a Bow Street magistrate and friend to Sebastian to oversee the investigation. Surgeon Paul Gibson of course becomes engaged in looking at the cause of some of the deaths.
For unknown reasons (and cynically, of course!) Hero’s father Lord Jarvis is involved, but how is the question. Lord Jarvis is a slippery character, Machiavellian. But oftentimes his actions end up placing his daughter in danger. And now a new chapter is opening in his life—or an old one continuing. As always Hero and his relationship is interesting.
An ongoing thread, the questions around Sebastian's mother ebb and flow throughout.
A concisely constructed regency mystery that just kept on giving right up until the last word on the page.
Once again I was left with a few loose ends and questions, particularly the last glimpse of Sebastian St. Cyr as he enters his front door. I just knew THAT was going to happen. How could it not?
The author's notes give a fine rundown on the fact and fiction in this tale along with a last macabre observation.

A Berkley Group ARC via NetGalley
Profile Image for Karen.
814 reviews1,208 followers
May 18, 2022
4 STARS


Don't think I'll ever get tired of this series. So many interesting storylines. And a little something brewing in Sebastian's little side investigation. This one brought to light the Ratcliffe Highway murders that had so many up in arms in East London over a century ago. Fascinating stuff. Looking forward to the next book to see what's coming next.
Profile Image for The Lit Bitch.
1,272 reviews402 followers
April 11, 2021
I absolutely love Sebastian St Cyr. I read the entire series last year in one long binge read. I adore the books and even if some of them have fallen into a bit of a formula, I still enjoy the characters so much. This one was high up on my TBR pile. I always set aside time in the early spring to read a new Sebastian mystery and I am never sorry about that.

The mysteries are intelligent, a little on the gritty side, and full of questionable characters all with their own motives. Going into this one, I was fully ready for just that and I wasn’t disappointed! But now that we are into book sixteen in the series, I am sure readers can’t help but wonder at what point will this series end? For me, I hope the answer is never but I also know that at some point all good things come to an end.

But until that day comes I am going to keep devouring the Sebastian mysteries and keep returning to my favorite characters. Some books in this series are able to be read as standalones and I think this one here could easily be read as a standalone if you want to check out the series but also don’t want to go back and read all the books to enjoy it!

This book explores the underbelly world of London’s brewing industry. I was very interested in that bit of the story and I was a little let down that it wasn’t explained more in this book. The concept of a corrupt brewing industry and licenses was explained well enough but I would have liked to have seen the author expand on it more and shown readers from of the nuances of the industry itself. This was a minor thing for me though. It wasn’t a make or break in the story but I had hoped to have become more familiar with the industry more as it was part of the core of the mystery itself.

I was also sad that we didn’t get more Hero in this book. She seemed to take a backseat to the mystery itself, as did Sebastian’s character and his ever contentious relationship with this own father as well as Lord Jarvis. I still feel like the author is setting readers up for a large scale conclusion to the series that will likely spread over a couple of books. That will likely involve Sebastian, his mother, his father, and Lord Jarvis and the new Lady Jarvis. In the meantime, I think the author is getting all those pieces in place while we the readers continue to enjoy the adventures and gritty mysteries of Sebastian as we do in this book.

This mystery was (as expected) twisty with many people with motives. I love trying to click the pieces into place before Sebastian solves them. But as always, I never seem to solve the mystery or the motives. I love how Sebastian’s mind works and how he puts everything together. As a character he is brash, bold, confident, and intelligent. I just love his character so much and am so excited to see where his story goes from here.

I do wish we had more Hero in this book because she matches Sebastian for wit, intelligence, and boldness. I love her character and can’t wait to see more of her in future book! If you love historical mysteries this book series is no doubt on your radar. It’s smart, gritty, complex, and well developed! I love this series and this book was an great installment!

See my full review here
Profile Image for Helen.
594 reviews16 followers
April 1, 2021
Many thanks to NetGalley and the publisher, Berkley for this Advanced Reader Copy and the opportunity to review What the Devil Knows. All opinions are my own.

Sebastian St. Cyr, Viscount Devlin is again righting a number of wrongs in What the Devil Knows, the latest in this long running series, this one set in 1814. We start with his summoning to the scene of the death noted in the very first chapter. What he finds brings to mind some earlier crimes, by the killer dubbed the “Ratcliffe Highway murderer.” That case was closed with the suspect’s “suicide.” But perhaps the real killer has struck again? Or perhaps a copyist, as our Viscount postulates. In any event, it’s someone who enjoys killing.

Of course, Devlin soon becomes personally threatened – doesn’t he always? We get scenes with his father-in-law, the hated Jarvis, and Hero, Devlin’s very resourceful wife, as strong a character as he is. I really enjoy the part she plays in these stories, even if she does tend to be somewhat over the top. It does give strength to her particular story within the story -- the horrific treatment of foundling children. This is not for the faint-hearted. It is truly terrifying, a horrible blot on human history that Ms. Harris reminds us of.

Other suspects for the murders are advanced. Our author offers up these little vignettes, but just like our protagonist, we are not deterred in our goal of finding the true culprit.

There’s also Devlin’s personal story – he has news of his mother. And a dead man’s son haunts his dreams. So many stories to be had here; it’s not a place to start the series, that’s for sure.

Precise, intricate plotting is a hallmark of these books. Devlin and Hero and the rest may seem modern in some sensibilities, but this is never a tale of modern times; we are always in Georgian England, sinister as it is.

Finally, “… a tale of ruthless greed and corruption that spanned decades” comes to an end. Jarvis ensures that no one messes with his family. And a surprise comes to the Devlin household.

The Author’s Note explains the history of the Ratcliffe Highway Murders and the resemblance to Jack the Ripper. She also explains how much is truth and how much fiction makes up her story. What the Devil Knows will keep you wanting to turn the page, eager to find out what happens next.
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