Before the Devil Knows

Gus Wheeler FBI Thriller #3

by R. John Dingle

Sometimes it’s not the devil you know…

When the disfigured body of a missing teenager is found in an unmarked grave in northern Maine, FBI agent Gus Wheeler and his partner arrive to investigate. They discover a second grave, but these remains are so badly burned, identification proves difficult. Yet the two bodies have something strange in a large lead cross laid upon each chest.

The locals are uncooperative, and the rural law enforcement is two steps behind. Enlisting help from a theology and biblical studies expert, they discover the murders are lifted straight from ancient scripture and the burials consistent with an archaic religious practice. Connecting the victims to a specific church adhering to a strict doctrine of the Old Testament creates more confusion than clarity.

As the investigation widens, the agents face threats and suspicion. Then someone inside the church begins leaving them clues, but are they friend or foe? With time running out, Gus must determine if their secret guide is leading them toward the answers or deeper into an underworld of twisted dogma and ancient rituals.

Genres: Mystery, Thriller, Suspense

362 pages, Paperback

Expected publication July 29, 2026

About the author

R. John Dingle lives and writes from a restored 200 year-old house, on a small island in Mid-Coast Maine. The often-haunting themes of the rocky coast, as well as a lifetime of experiences in and around New England’s small towns, farms, and cities, provide excellent inspiration for the tones and moods reflected in Dingle’s mysteries and psychological thrillers. He is the author of the critically acclaimed and multi-award nominated Gus Wheeler FBI Thriller series, which includes Karma Never Sleeps, Wings of Madness, and Before the Devil Knows.

Reviews

[Heather Flaherty · Rating 5 out of 5]

I. Absolutely. Loved. This. Book. This is the third book on the Gus Wheeler FBI series and I am so invested in them. I am sitting here waiting patiently for the next one. (Hint hint) Gus and V find themselves in Northern Maine investigating unmarked graves buried with lead crosses. It seems to be connected to a religious community but nobody is talking and they don’t like strangers asking questions. Can they find out what’s going on before they end up in the next unmarked graves buried?

[Jacklyn B · Rating 5 out of 5]

I was so excited to start this book - I absolutely LOVED Karma Never Sleeps & Wings of Madness where we meet FBI profiler Gus Wheeler and Vanessa Lambert (I highly recommend reading them!! But please note The Devil Knows can be read as a full standalone!)

I was hooked right from the very first chapter! This is a book that will have you staying up way past your bedtime because you just can’t put it down. This book is fast paced with twists and turns and secrets with just the right amount of creepy feelings sprinkled on top. Gus and Vanessa are quickly becoming two of my favorite characters. Their banter and chemistry is top notch!

No spoilers here - but do yourself a favor and make this your summer thriller read!!

✨What To Expect:
🧠Psychological Thriller
🔪Dark Crime Thriller
👀Old Testament / Cult Vibes
⁉️Suspense & Tension & Mystery
🏡Small Town Maine
🌪️Twists & Turns
🔍Police Procedural

[Celeste Velocci (bookrecs_by_celeste) · Rating 4 out of 5]

Another great read in the Gus Wheeler FBI Series! I’m so excited this series is continuing and I cannot wait to see what unfolds next!

Thank you so much to the author R John Dingle for my gifted arc of Before the Devil Knows. I will read anything he writes it’s just that good!

I absolutely loved the religious tie in with this read. It added so much to the story and was such a unique premise. It was dark , psychological, and its cult like vibe had me questioning everyone and everything.

When a missing teen is found disfigured in an unmarked grave and strange religious practices begin to come to light Agent Gus Wheeler and his team will leave no stone unturned until the case is solved.

Dingle’s writing and his attention to detail sets his crime fiction thrillers apart from the rest. Be sure to add this twisty ride to your summer tbr it releases July 29th!

I cannot wait for book 4 especially with that ending!!

[Jessa Layne • readwithjessa · Rating 5 out of 5]

When the body of a missing teenager is discovered in an unmarked grave in northern Maine, FBI agent Gus Wheeler and his partner are called in to investigate. What starts as a murder case quickly becomes more disturbing when a second grave is found and both victims are discovered with large lead crosses placed on their chests. As Gus digs deeper with the help of a theology expert, the investigation leads to a secretive church, ancient religious practices, and a mysterious insider leaving clues. With threats mounting and trust in short supply, Gus must figure out who is helping him before the case pulls him further into a world of twisted beliefs and deadly rituals.

This was an amazing read and my first book by this author, even though it is the third in the Gus Wheeler series. I usually do not read religious themes in my book, but I loved it in this book! The religious elements here were fascinating and added so much to the story, creating a truly unique plot. The dark, psychological atmosphere and cult like vibes had me questioning everyone and everything. The secluded Maine setting made it even more eerie too. The story was fast paced, twisty, and impossible to put down- I finished it in 2 sittings. Also, that ending left me wanting book 4 ASAP and also ready to go back and read the first two books.

Thank you Thriller Book Lovers: The Pulse and the author R. John Dingle for the gifted copy! This book is out July 29, 2026!

[Lauren Self · Rating 4 out of 5]

BEFORE THE DEVIL KNOWS by @r.johndingle
📖 book review • out 07.29.26
⭐️⭐️⭐️⭐️

thanks to the author for my box & my signed copy! they all look so good together 😍 @tulepublishing @thrillerbookloversthepulse

book three is by farrrr the darkest book of this series and based on that last page 👀 we may be going even darker the next round. i’m here for it!!!

gus wheeler is back (swipe to see the synopsis on the back of the book) & if you haven’t checked these books out yet, you’re totally missing out. Karma Never Sleeps is one of my favorite thriller debuts, and I love that I’ve had the chance to read every book in the series early! I treasure my copies and hope more people in the world see them, because they’re truly gripping stories (and book 3 will probably have you clutching your pearls) buckle up!!

[Amanda · Rating 4 out of 5]

the fact that the first chapter had me already saying wtf at the end, i immediately knew this was going to be a good one.

this was my first book by this author, & he did not disappoint! i was hooked pretty much from the start. the eerie atmosphere in the small town, where there seems to be eyes everywhere, kept me fully invested! it made me put in my detective hat on, trying to figure everything out before the characters did. i got a couple of twists, but that one near the end? i did not see coming! (can’t get them all, lol)

gus & vanessa made a great team. i loved their friendship & the banter between them both. she had me laughing more than once. “skip intro” 😂

overall, i definitely enjoyed this one. i loved trying to piece everything together, & the ending has me dying to know what happens next! although this is the 3rd book in the series, it can easily be read as a standalone.

𝐫𝐞𝐚𝐝 𝐢𝐟 𝐲𝐨𝐮 𝐥𝐨𝐯𝐞:
♡ fbi investigation
♡ detective thriller
♡ religious retribution
♡ murders/disappearances
♡ suspenseful & twisty
♡ small town
♡ fast paced
♡ short chapters

thank you r. john dingle for the advance copy in exchange for an honest review.

[Samantha Milbert · Rating 5 out of 5]

⭐️⭐️⭐️⭐️⭐️
Book number 3 of the Gus Wheeler series (however can be read as a standalone and this was the first book I have read in the series). I had the opportunity to read this complimentary in exchange for an honest review and it did not disappoint! It’s a great read for those that are into fbi or detective thrillers, it had me on the edge of my seat until the very end. The two fbi agents, Gus and V, complement each other with their different personalities. The story is set in very rural northern Maine which adds an additional set of challenges for the agents to solve this complex and multi layered case. Lastly, this book was very fast paced and made it quite difficult to put down which is essential in this genre.

[Mary · Rating 5 out of 5]

Book Title: Before the Devil Knows (Gus Wheeler FBI Thriller Book 3)
Author: R. John Dingle
Publisher: Tule Publishing
Pub Date: July 29, 2026
Dates Read/Listened: April 14, 2026 – May 9, 2026

🗣️ 𝚀𝚞𝚒𝚌𝚔(𝚒𝚜𝚑) 𝚃𝚊𝚔𝚎: R. John Dingle has really outdone himself this time, and it is my personal opinion that Before the Devil Knows is now the best book in the Gus Wheeler series. This one really hit for me, and the religious aspect of the deaths made it feel even more ominous. The small-town vibes abound, and no one is quick (or willing) to help Gus and Vanessa find the killer. Or killers…? 🤔 It was such a creepy and action-packed ride that never lets up. The conclusion was positively wild, and it was the perfect way to wrap up this FBI thriller. I love Gus and V so much, and they are such easy characters to root for, so it’s always hard when you see anything bad happen to them, though you know that’s basically going to be a given. I was definitely left wanting more, and I can’t wait to see where the next book takes us! PSA: Not for the faint of heart. 😉

T͏h͏i͏s͏ B͏o͏o͏k͏ i͏n͏ 5͏ E͏m͏o͏j͏i͏’s͏ o͏r͏ L͏e͏s͏s͏: 🪦✝️🚓🎶

𝙱𝚘𝚘𝚔 𝚁𝚊𝚝𝚒𝚗𝚐: 🌟🌟🌟🌟🌟

I received a complimentary copy of this book. Opinions expressed in this review are completely my own.

[Becky • bookmarked by becky · Rating 5 out of 5]

Mr. Dingle, can I just say... your books keep getting better and better!

This series has everything I love: fast pacing, short chapters with those mini cliffhangers (”just one more chapter” vibes), dark psychological depth, unsettling trauma, and twists that keep coming.

In Before The Devil Knows, the focus is on religious fanaticism, which gives this one an especially eerie edge. I find the psychology behind it fascinating, while also feeling genuinely unsettled by what people were willing to do in the name of faith.

And Gus and Vanessa? They just keep getting stronger as a duo. By now, they feel like old friends. We know what makes them tick, we understand their humor, and their partnership feels authentic and earned. I love experiencing the investigations through their perspectives—their intelligence, instincts, and observations make every case feel like I'm part of the duo. And honestly, Gus's brain full of racing monkeys makes me feel very seen. 😂

Dingle, I’m a forever fan!!! Dingle writes clever detective stories packed with memorable details. I loved Vanessa's "final girl" references, the The Shining nods, and I swear I spotted the previous two titles in the story - a little play on words maybe???

Needless to say, I'm already impatiently waiting for Book 4.

Final Verdict: 👍 100% yes! An excellent crime novel that blends forensic investigation, psychological suspense, and religious fanaticism into a gripping mystery. Plus, Gus and Vanessa are investigators you'll absolutely want to spend more time with.

[Jessy · Rating 5 out of 5]

Genre: Thriller
🫆 FBI Thriller
🩸 Murder
🪦 Unmarked Grave
⛪️ God’s Will
👮🏼 Religious Clues
❓ Who is behind it

My Take - Speechless! Wow! Book 3 hit hard. The emotions, suspense, twists, and turns. The uncertainty. I was on a roller coaster. I did not know how to feel. I was on edge with every chapter I turned the page to. I love Gus and Vanessa! They are not just partners. They have such a special friendship and bond. Together they are a dynamic duo. In this third book you can really tell their character growth and see their personalities come out. The narrator in this book had me a little twisted. Like what is going on here. The diaolgue between characters was top notch and enaging. I felt like I was deep in this investigation with Gus and Vanessa.
Quick Summary -
Gus and Vanessa are at it again in a small town of northern Maine. Called into investigate a body found in an unmarked grave. This investigation had challenges right from the start. But in Gus and Vanessa fashion they were determined to get to the bottom of it. Gus and Vanessa noticed religious clues right away at the site of the unmarked grave. They knew they were in a little over their head. Therefore, they called in a religious expert to help the decipher the clues. Is the church and their members really responsible?

[Nicole Cruz · Rating 4 out of 5]

⭐⭐⭐⭐/5

📚 Before the Devil Knows by R. John Dingle 📚

This is my third ARC from R. John Dingle, and at this point, I’ll pretty much read anything he writes! 🙌

What really hooked me with this one was the cult aspect. 👀 I always love a good cult storyline, and this book delivered plenty of mystery, suspense, and twists to keep the pages turning. The writing style is so smooth and accessible that I flew through it without ever feeling bogged down.

I also loved that the story takes place in Maine. 🦞🌲 Being from New England, it made the setting feel even more immersive and familiar. Another highlight was the partnership between Gus and V. Their dynamic continues to be one of my favorite parts of this series, and I loved spending more time with them.

The Gen Z lingo sprinkled throughout the book gave it a modern feel and even had me laughing a few times. 😆

Most importantly, I’m so excited that this series is continuing! 🎉 There are definitely more adventures ahead for Gus and V, and I’ll be first in line to read them.

If you’re a fan of fast-paced mysteries, cult-centered storylines, memorable characters, and easy-to-devour writing, this series is absolutely worth checking out. 📖✨

Thank you to the author and publisher for the ARC in exchange for an honest review.

[Bola · Rating 5 out of 5]

I’ll be honest, was skeptical going into this one based on the title. Horror isn’t really my thing, and I typically stay away from books that heavily involve the devil or demonic themes. But I’m so glad I gave this book a chance because it completely won me over.

At its core, this is an investigative thriller, and that is exactly where it shines. When the body of a teenager is discovered, it sets off a chain of clues leading to another set of remains… and then another… and another. What starts as a single case quickly evolves into something much bigger, and I was hooked from the very beginning.

One of my favorite parts of the book was the dynamic between Gus and V. Their partnership felt natural, and I loved following them as they unraveled the mystery piece by piece. The investigation was compelling, the clues were intriguing, and the pacing kept me fully invested.

This book kept me engaged from page one, and I found myself constantly wanting to read just one more chapter. Before I knew it, I was completely immersed in the story.

Now I feel like I need to go back and read the first two Gus Wheeler Thrillers because if they’re anything like this one, I’m all in. A gripping, well-paced thriller that exceeded my expectations in every way.

[leslie mayorga · Rating 4 out of 5]

I was super excited to be able to receive an arc of this book! The last one was great and this one is no different. Really great book and series in all. R. John Dingle became my auto read author. And soon my autobuy author I just need to set up my library so I can display them! I’m a big fan of fbi series whether it’s a tv show or book. But by far John is my favorite and to go to for an fbi thrill. What I really enjoy about the way he writes the book and the characters is that you get to follow Gus and Vanessa solving the crime. Looking for clues and investigating who the killer is. And their reasoning behind it. Love to see their thought process. In this book it dealt with religious beliefs and a sort of cult type of vibe. And if you’ve seen those episodes with religion and cults you already know the vibe it’s going to give. It gets crazy when Gus starts to discover bodies with unknown identities. You read that right. Bodiessssss not one, two or three but many. Again such a great chase, very interesting, fast paced and it catches your attention. Absolutely love Gus and Vanessa. I can’t wait to continue the next book in this series. Hope to see more of Gus.

Would I recommend?
Yes!

[Carey · Rating 5 out of 5]

This series just keeps getting better with every book, and this third installment is my favorite yet! I was hooked from the very first page and genuinely could not put it down. The pacing was perfect, with twists that kept me guessing and just enough suspense to make it impossible to stop reading.

One of my favorite things about this series is the characters. They continue to grow with each book, and I’ve become so invested in them that it feels like catching up with old friends—if those friends constantly found themselves in the middle of heart-pounding mysteries.

The author’s writing style is incredibly engaging, making every chapter fly by while building tension at just the right pace. I was fortunate enough to read an advance copy, and it exceeded every expectation I had.

If you’ve loved the first two books, you’re going to be blown away by this one. And if you haven’t started the series yet, now is the perfect time—because this third book proves the series only gets stronger. I can’t wait to see what comes next!

*I received a complimentary advance copy in exchange for a review.

[Kristin (Readwithdubs) · Rating 5 out of 5]

I had the honor and privilege of reading an ARC of this high anticipated release and (no surprise here) it did not disappoint!

@r.johndingle has crafted yet another addicting mystery centered around our favorite FBI duo, Gus and Vanessa. The stakes were high, the twists were twisting and I couldn’t put this book down.

I absolutely love the dynamic between these two characters - the witty banter and fierce loyalty that’s been built and has grown since book one is so fun to read. The best part is how, once again, this can absolutely be read as a standalone BUT do yourself a favor and read them all.

It’s evident that the author really did his homework for this story - I won’t say much more because I fear I’ll ramble and give things away 😅 but I will say that I 100% recommend you add this to your summer TBR.

Now that the trifecta is complete…I can only hope book four is in the works 😳

Before the Devil Knows is making its way to a bookstore near you on July 29th 🗓️

[Nicole Alycia · Rating 5 out of 5]

Gus and V are back and their new case takes them to rural Maine where they have to solve a string of Old Testament style murders.

This book was SO good! Such an easy 5 stars! And I swear this series gets better and better each book! This was such an interesting case and you get totally drawn into the story in the first chapter! The quick, intense chapters keep you totally absorbed in the story and I could not put this down! And the Old Testament/religious zealots themes made the story so intense! And the ending has me so excited for the next book!

If you enjoy a fast paced FBI thriller then I highly recommend picking this series up!
While this book can technically be read as a standalone there are references to the previous two books so I’d recommend reading them first! They’re definitely worth the read!

[Tricia · Rating 4 out of 5]

After reading the first two Gus Wheeler books, I was thrilled to read Before the Devil Knows. It did not disappoint! Set in a small Maine town, Gus and his partner Vanessa are investigating a series of murders. As the victims are discovered, they find that the causes of death are unusual and suggest that the killer was motivated by strict Old Testament religious beliefs. The victims were punished for their perceived sins. To point him in the right direction, Gus consults an expert in religious theology. Together, they try to interpret the strange causes of death and the significance of objects left at the graves. Gus and Vanessa try to untangle the truth before they become the next victims.

The religious elements definitely give this story a spooky feel, almost like an eerie campfire tale. The ending is a bit of a cliffhanger and I can’t wait to read the next one!

[Nath · Rating 5 out of 5]

Thanks to Bookstagrammer Bone Chilling Books for my ARC. I love the Gus Wheeler series, and after reading the first book back in January, I was excited to get my hands on the newest release!

This is by far the best book in the series so far. It delivers nonstop action and suspense from beginning to end. I finished it in a single weekend because I simply couldn’t put it down.

Just when I thought I had everything figured out, the story took a twist I never saw coming. The author never disappoints, and this book kept me guessing until the very end. Reading this book gave me serious Criminal Minds vibes, which made it even more enjoyable.

I am already ready for the next book and can’t wait to see what happens next in the Gus Wheeler series!

Rating: ⭐⭐⭐⭐⭐

[Stephanielikesbooks · Rating 4 out of 5]

My fellow Thriller Book Lovers The Pulse members and I really enjoyed this new Gus Wheeler story, book 3 in the Gus Wheeler FBI series. With its short chapters, many good twists, and tense action scenes, this one pulled me in.

I liked the small town rural Maine setting and the religious cult storyline. The members of the cult were really quite creepy. Gus and Vanessa’s (his colleague) sibling-like relationship continued to evolve which was nice to see.

I liked seeing how the murder investigation unfolded and how the various elements came together in an exciting ending and a great set-up for book 4.

I recommend this really well-done series!

Thanks to the publisher for the complimentary digital copy. All opinions are my own.

[Cat · Rating 5 out of 5]

Gus and Vanessa are back at it again. I love the dynamic of their partnership and I love reading about their cases. They always seem to find themselves in danger but it’s all part of the job. This book had its hooks in me from the very beginning. It was like watching a movie on screen and I couldn’t look away. It was action-packed and fast-paced. I felt like I was trying to solve the case right along with them. Just when you think you know how things are going to end, there’s a twist that throws you for a loop. I loved every second of it and can’t wait to devour the next book!

[Sheri · Rating 5 out of 5]

Wow! That is all I need to say about Gus Wheeler’s 3rd book in this FBI series. Gus and his partner, Vanessa, are called to northern Maine to solve deaths of a mysterious nature that appear to be related to religion. Think The DaVinci Code but without the multiple country trip.

I would recommend reading all the books in the series in order to get the full effect of Gus and Vanessa and how their partnership has evolved. Gus is serious and Vanessa is funny and both do their jobs very well.

I am in love with this series and already can’t wait for the next book.

[Pelusa Clements · Rating 5 out of 5]

I received a complementary review copy and…I was blown away!!! Great book, page turner and the twist..wow!!!! Now, I have to read book 1 and 2!!!! I highly recommend it!!!!

[Dawn (bookscatsandbingeing) · Rating 5 out of 5]

Easy five stars! This series keeps getting better and better. That ending! R. John, we got beef! I need the next one NOW.
Gus and Vanessa are a fab duo. V is the perfect final girl.

[Kristin · Rating 5 out of 5]

With two victims found in unmarked graves with lead crosses, Gus Wheeler and Vanessa are brought in to help investigate the matter. In this rural town in Maine, the locals are not keen to help the FBI; they are used to taking matters into their own hands. Gus and Vanessa retain the help of a theology expert and soon tie the murders back to a specific church. Someone inside is slipping them clues, but are they to help or steer them wrong? The clock is ticking before the next murder and Gus and Vanessa need to find out who is behind all these murders.

Wow.. these books just keep getting better and better. I absolutely love this author’s writing style. I was pulled in from the very first page all the way to the end (which I’ll get to in a bit). I couldn’t put the book down, and even read during the day when I was supposed to be working (shh, don’t tell!).

The dynamic between Vanessa and Gus only gets better and better. They play off each other so well and are the perfect work partners. And the atmosphere of this rural town is perfect for the plot. There’s so much build up throughout the book with so many suspects! I feel like I knew it wasn’t one particular person, but even knowing that, I thought it was definitely a different one, but I was wrong… again.

When the FBI realized who it was I also realized who it was, and sheesh, I was shocked! There was then another twist that left me shocked too!! And oh, the end, the very end of the book was another shocker. I don’t know where this author comes up with his ideas, but they are fantastic. This book isn’t even released yet, and I’m already excited for the next one. Seriously, everyone absolutely needs to read this book and the first two in the series (if you haven’t already).

Get your pre-orders in because you don’t want to miss out!

[Emma Marshall · Rating 5 out of 5]

The story hooks you by the throat from the very first chapter. R. John Dingle immediately drops us into the terrifying mindset of a cult mindset, where a child named Adam is held accountable for his “sins” under the fast and furious doctrine that death is the only understandable payment. The choice of the name Adam is a brilliant, layered piece of religious symbolism, and the emotional weight is dialed up to an absolute ten when he realises his own family lies within the crowd of those judging him. It is a masterclass in how to start a thriller!

Advertisement

Privacy Settings
Just when you think you’ve pinned down the tone, the narrative beautifully upends your expectations. It introduces Phyllis, a retired hobby-hunter who inadvertently uncovers a crime scene. She has such a wonderful, sharp, Joyce from the Thursday Murder Club presence that balances out the darker elements of the investigation perfectly. I feel this is an incredibly clever, winding procedural that manages to be both chilling and deeply charming all at once.

Beyond the brilliant tone shifts, R. John Dingle delivers an absolute masterclass in atmospheric setting by plunging us into a deeply isolated, small-town environment. The drop in phone signal, the sparse population, and a local sheriff who firmly emphasizes just how home-based and insular this community is adds a brilliantly eerie layer to the mystery. It proves to be the ultimate obstacle for Gus and V – obvious city dwellers accustomed to structured organisation and easy communication. Forcing them into a rugged country setting where neighbours live in self-imposed isolation and expect to be left completely alone creates an incredible friction that stalls the investigation and keeps the reader entirely on edge.

Advertisement

Privacy Settings
Adding to this brilliant, slow-burning tension are the clever pop culture Easter eggs woven throughout the narrative. From wry comments about the stereotypical “final girl” in a horror movie to the lingering, eerie feeling of stumbling into a real-life Bates Motel while navigating the isolated town, these subtle nods are incredibly fun for thriller fans. It acts as just enough foreshadowing to suggest that the story is heading into even darker, more unsettling territory. It shows a wonderful self-awareness in the writing that heightens the psychological dread without ever breaking the immersion.

As the investigation deepens, the narrative takes on this incredible, high-octane energy that feels like a brilliant mashup of Criminal Minds and Hot Fuzz. You get the dark, gritty procedural tension of a complex criminal investigation paired with that distinct, eerie feeling of big-city detectives trying to crack a tight-lipped, insular rural community. It creates a fantastic momentum where the stakes are constantly escalating, making the pages fly by as Gus and Vanessa try to peel back the layers of this town.

Beyond the dark, psychological tension of the plot, the narrative introduces a brilliant human element: the steep learning curve of urban investigators trying to decipher rural life. Gus and Vanessa can’t rely on their usual high-speed organisation or standard city resources here. Instead, the story places immense weight on their willingness to adapt, respect, and learn how to work alongside the local country folk. This clash of mindsets elevates the book from a standard plot-driven puzzle into a genuinely compelling character study.

Advertisement

Privacy Settings
The book excels at creating a sense of deep-seated paranoia, particularly in how it explores the fracturing loyalties within the cult-like community. By utilising a rotating perspective – shifting between the agents hunting for truth and characters who possess a dangerous amount of insight into the mystery – the plot forces you to scrutinise every piece of assistance. When a seemingly cooperative individual begins leaving a trail of breadcrumbs for the investigators, the shifting points of view make it impossible to tell whether this person is an ally trying to escape the community, or an extremist quietly working to ensnare new members into their radical beliefs. It’s a masterful way to handle suspense without relying on overt action.

The structure of this mystery is beautifully deceptive. While the overarching threat of extreme cult-like actions provides a constant layer of psychological dread, the story actively peels back layers as it progresses. Hitting a turning point at the halfway mark was incredibly satisfying, but the revelation waiting in the final quarter blows the scope wide open. It proves that the dark elements outsiders see are just symptoms of a much deeper, more systemic rot embedded within the history of the small town itself.

Advertisement

Privacy Settings
As the narrative barrel rolls toward its conclusion, R. John Dingle throws one final, masterful curveball that completely shifts the thematic landscape. It becomes brilliantly clear that Before the Devil Knows isn’t merely an exploration of an insular small-town environment or the dark mechanics of an unhinged religious culture. This late-stage revelation brings heavy, intense tonal shifts that deeply impact every character’s actions, ramping up the emotional weight and making every decision feel incredibly high-stakes as the puzzle pieces finally snap into place.

Favourite characters:

While Gus might be the established lead of this series, it was his partner, Vanessa, who completely stole the show for me this time around! Watching her navigate the rigid, eerie isolation of this small-town community was fantastic. As a city dweller used to high-speed organisation, she brings such a sharp, compelling energy to the dynamic. Gus is a great anchor, but Vanessa’s perspective, her resilience, and the way she holds her own against a wall of rural silence easily made her my absolute favourite character in the book.

Advertisement

Privacy Settings
Favourite quotes:

“This is feelin’ a lot less Norman Rockwell and a lot more Stephen King.”

“And Gus wondered how the universe worked, how it could line up all the tiny details and steps throughout someone’s entire life to bring them to this spot, to this end.”

How it ends:

The book culminates in a spectacular, high-stakes countdown to midnight that guarantees you’ll be reading the final pages at breakneck speed. With a dangerous threat officially out in the open, the suspense shifts beautifully. It’s no longer about uncovering secrets; it’s a desperate race against time. Even with all the guilt exposed and the villain(?) unmasked, Dingle keeps the audience entirely in the dark about how the scales will ultimately balance. The absolute unpredictability of how justice will manifest creates a brilliantly volatile ending where no one – not even the agents on the ground – is safe.

Favourite part:

Advertisement

Privacy Settings
What completely sealed this book as a standout read for me was a massive “oh!?” moment that completely upends the narrative. It’s one thing to sit back and piece together your own theories as a reader, but R. John Dingle pulls the rug out from under both the investigators and the audience in a way that feels incredibly earned. It isn’t just a simple plot twist for shock value; it’s a brilliant conceptual shift that elevates the entire story, transforming what appeared to be an isolated, small-town incident into a much larger, darker mystery to uncover. It completely expands the scope of the plot and leaves you breathless.

Rating out of 5:

Without a doubt, this is my absolute favourite of R. John Dingle’s books to date. It is a beautifully structured in psychological tension, pacing, and thematic evolution. I particularly loved the cheeky, subtle nods woven into the books in the series so far that connect this story and the second book back to his very first novel. While this book completely functions as a standalone mystery – meaning you do not need to commit to an entire series if multiple books feel overwhelming – those clever easter eggs add a brilliant extra layer for returning readers.

Advertisement

Privacy Settings
Even when a technical glitch with my tablet forced me to restart the book after chapter 70, rereading the meticulous build-up only made the explosive, clock-ticking conclusion feel even more rewarding the second time through. I honestly could not find a single thing I did not love about this story. So this gets a full and accurate five star rating from me!

If this sounds like your kind of story, you can find it here 👇

https://amzn.to/4cXn7qS

[Lesa · Rating 5 out of 5]

Well John has done it again!!!! This is a phenomenal book! The writing was very well done and very captivating! I was hooked the whole way through! Gus and Vanessa are absolutely my favorite power duo! Such a great friendship between them. I can’t wait for more.

[Caroline | dogtailsandcrimetales · Rating 5 out of 5]

★★★★★

“Hell is empty and all the devils are here.”

Two teenage bodies are found in unmarked graves in rural Maine. Each victim has a lead cross, tying them to each other and to a local church that’s giving seriously cultish vibes. Its leader is known for that classic fire-and-brimstone mentality. The locals won’t cooperate with law enforcement, not even the victims’ families. This is the kind of place where people handle their business and shut out outsiders. As Gus and Vanessa start digging, the town closes ranks fast and makes it very clear they’re not welcome. Just when it feels like a dead end, a member of the church starts dropping clues that could finally bring some justice.

John absolutely understood the assignment (IYKYK)!

Vanessa and Gus still pass the vibe check, and honestly, I don’t think I’ll ever get tired of them. There’s so much love and respect between them, mixed with the kind of sibling-level chaos that makes their dynamic feel real and keeps things from getting too heavy. And trust me, this book gets dark!

“Gus wondered how the universe worked how it could line up all the tiny details and steps throughout someone's entire life to bring them to this spot, to this end. If it was divine intervention, he thought, there was nothing divine about it.”

John mentioned he’s had this idea for a while, and I need to know how his brain works because these stories are so tightly woven, clever, and just ridiculously well planned. Once again, I was completely blindsided by the twists he threw at us. At this point, I should expect it, but nope, he still gets me every time. The ending was satisfying, with just enough of a hook to leave me wanting more. I am fully choosing to see it as a setup for book four, especially after that new three-book deal was announced!!

If you love dark, twisty stories packed with shocks and turns you won’t see coming, and FBI agents who are nothing like what TV has trained you to expect, you need to check out the Gus Wheeler universe. If you’ve been here from the start, clear your July schedule because you’re not going to want to miss this one. And if you’re the type who jumps into a series midway, you can read this as a standalone, but you’ll get so much more out of Gus and Vanessa if you know their history.

And finally, thank you to John for the gifted copy. Between the announcement, getting the ARC, and hearing about the new book deal, I’ve basically been in a constant state of happy dancing. All opinions are my own.

[Julie Maleski (juliereads_alot) · Rating 5 out of 5]

Thank you to Thriller Book Lovers The Pulse and the author for inviting me to be a part of this book tour, and to Tule Publishing and The Pulse for the gifted e-ARC...this is my honest review.

📱 Before The Devil Knows📱
Author: R. John Dingle
Pub Date: July 29, 2026
Publisher: Tule Publishing

MY RATING: ⭐⭐⭐⭐⭐

Wowwwww. Before The Devil Knows, the third book in the Gus Wheeler FBI Thriller series from R. John Dingle, has secured its spot as my favorite book in this series -- so far. This unputdownable thriller is fast-paced and action-packed, with unrelenting suspense and shocking twists that had me reading as quickly as I could.

In this book, FBI Agents Gus & Vanessa are assigned to a new case when the disfigured body of a missing teenager is found in an unmarked grave in a remote and isolated town in northern Maine. As they investigate, they are up against townspeople who want nothing to do with out-of-town law enforcement because they take care of problems themselves, and facing religious zealots who believe it's their duty to punish those who don't follow the church's teachings. Gus & Vanessa aren't just investigating the case though, they're pulled right into it as the townspeople attempt to be sure they know just how unwelcome they are.

This dark thriller had such creepy vibes, with that foreboding sense of being watched at all times and the feeling that you can't trust anybody. This town had eyes everywhere and the tension that created was almost palpable.

R. John Dingle, I don't know how you do it, but this series just gets better and better with each book! Learning that Dingle signed a new 3-book deal for even more Gus Wheeler books to come had me doing a happy dance yesterday. If you're not reading this series yet, you're seriously missing out. Could you read this book as a standalone? You could, though I don't know why you'd want to miss out on the first two books!

This series is perfect for thriller fans who love action-packed suspense, police or FBI procedurals, creepy investigations into killers, and quirky main characters who are both badass & endearing. This book comes out at the end of July and you simply must read it. (And there's still plenty of time to read the first two books in the series before this one is released!)

#BeforeTheDevilKnows #RJohnDingle #thrillerbookloversthepulse #TulePublishing #booktour #gifted #fivestarreads #mustreads #thrillerlovers #thrillerreads #thrillerseries #bookreviews #bookrecs #bookrecommendations

[Melissa Andrade · Rating 4 out of 5]

Thanks bonechillingbooks for the complimentary ARC

Weird noises are coming from inside the house. Adam Carson woke up. He calls for his mom and dad, but no one answers. He gets up and goes towards the noise, but suddenly, someone grabs his arm, covers his face, and drags him outside. He tries to fight, but it is all for nothing, and he is now tied to a tree. The voices stop. Silence. Then, someone, a voice that the boy clearly recognizes, says: It is God's will. A few days later, two dead bodies are found in an unmarked grave. Both were buried with a large lead cross, and next to it are some weird religious writings. That is when FBI agents Gus Wheeler and Vanessa Lambert are called to investigate, but they know something is going on when the locals refuse to talk to them, the police know close to nothing, and a suspicious Father has the community in a tight grip.

This was the first time I’ve read something from this author, and I was locked in from the very beginning. The way he writes about the crimes, the locals, and especially the religion, without any prejudiced views, was a pleasant surprise to me. He knew how to build a compelling crime thriller using a sensitive topic without falling into classical stereotypes. Which makes Before the Devil Knows way more enjoyable since the reader can also learn about various symbols within the religion, and their potential for nefarious uses, while keeping their eyes glued for what will happen next with Gus, V, and who are killing these people.

However, there are some minor things within the narrative that bothered me. One of them was the number of jokes about Vanessa being a final girl. The first time I found it funny, it was a nice input, using a pop culture element. But I didn’t cackle when I read it for the 5th time. The same thing happened to the number of times the author referenced his previous works. I mean, I get it that it needs to entice curiosity from the reader, especially if it is someone like me who is reading any of his books for the first time. But it also needs to be careful not to overuse it to the point it becomes excessive. Which is exactly what happens here.

Overall, Before the Devil Knows is a great crime thriller story that will grab your attention from the very first chapter, as it did with mine. It is only God’s will.

[Rae B Reads · Rating 4 out of 5]

Some thrillers rely on one jaw-dropping twist to carry the entire story. Before the Devil Knows takes a different approach. Instead, it steadily builds tension through a layered investigation, an unsettling cult atmosphere, and a mystery that becomes more dangerous with every chapter.

At its core, this is an investigative thriller, and that’s where it shines. I loved following FBI Special Agent Gus Wheeler and his partner, Vanessa. Their partnership felt authentic from beginning to end. There was no forced romance or unnecessary drama, just two intelligent investigators who trusted one another completely. Their dynamic quickly became one of my favorite parts of the book.

The atmosphere was another standout. From the isolated church and underground grotto to the religious symbolism woven throughout the investigation, the setting created a constant sense of unease. Rather than relying on graphic violence, the story built suspense through psychology, manipulation, and the fear of what was lurking beneath the surface.

The investigation itself kept me engaged. Each clue built naturally on the last, and I appreciated that the breakthroughs came through actual detective work instead of convenient coincidences. The second half especially found its rhythm, transforming the story from solving past murders into a race against time to prevent the next one.

That said, this wasn’t quite a five-star read for me.

A few reveals became predictable before they happened, which took away some of the surprise, and I found myself wishing more members of the church had been developed as memorable suspects. By the final act, the mystery had narrowed enough that some twists didn’t land with the impact I was hoping for. I also thought the introduction of the larger mythology near the end felt more like setup for future books than something fully integrated into this story.

Even so, this is an easy recommendation for readers who enjoy investigative procedurals, cult-centered thrillers, and slow-burn mysteries that steadily escalate into an intense finale.

I’ll absolutely continue with the Gus Wheeler series, and I’m curious to see where the larger story goes next.

Thank you to Bone Chilling Books for providing me with a Kindle ARC in exchange for my honest review.