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He made a fatal mistake.

He lusted after the wrong woman. Let his need take over. Cassius “Cass” Striker knew that he should have never touched the sexy FBI agent, but he gave in to temptation and had the best one-night stand of his life with Agnes Quinn. It should have meant nothing. He should have been able to walk away…

He can’t walk away. If he does, she’s dead.

His enemies know about Agnes, and they plan to use her against him. He’s the leader of one of the most notorious motorcycle clubs in the US. His name stirs fear into the hearts of nearly everyone…and he has a giant target on his back. Those who want to bring him down have been looking for a weakness to use against him—they think they found that weakness in the form of Agnes. Now he either saves her or he watches her die.

She doesn’t need saving, but it’s super sweet of him to try.

She fell for the bad guy. Not something that typically happens given her occupation, but Agnes couldn’t quite help herself. She’d been drawn to Cass from the first moment, and now the world—uh, the “underworld” thinks that they are hot and heavy, that she’s a way to break the unbreakable leader of the Night Strikers. Cass is vowing to protect her, but the only way to do that?
Enter his world. Accept his claim. Eliminate all the threats that exist to them both.

She has to go in undercover, continuing to pose as Cass’s lover as they embark on a cross-country trip. She has to follow his rules. She has to seemingly sever her ties with the FBI. In other words, Agnes has to go deep and hard in an undercover mission as she and Cass take out some seriously bad guys. No worries, though. Agnes does love an undercover mission, so this should be fun.

The case is a nightmare. It is not fun. And if Agnes flashes her sexy smile at him one more time…

Cass is sure that he’s lost his soul, and he’s not even sure where his criminal life ends and the real man that he’d once been begins. He knows one thing, though. Agnes is trouble—and he wants her. Wants her so badly that maybe he’ll let the dark side of his nature off the careful leash he holds. And he’ll take what he wants as he damns the consequences. Threaten her? Try to use her against him? Worst mistake his enemies could ever make because Agnes is his.

Cass was never meant to be a protector, but he sure is one hell of a predator.

313 pages, Kindle Edition

First published December 30, 2025

63 people are currently reading
116 people want to read

About the author

Cynthia Eden

309 books6,808 followers
Award-winning author Cynthia Eden writes sexy tales of contemporary romance, romantic suspense, and paranormal romance. She is a New York Times, USA Today, Digital Book World, and IndieReader best-seller. Since she began writing full-time in 2005, Cynthia has written over one hundred novels and novellas.


Cynthia lives along the Alabama Gulf Coast. She loves romance novels, horror movies, and chocolate. Her favorite hobbies including hiking in the mountains (searching for waterfalls) and spelunking.

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Displaying 1 - 29 of 29 reviews
Profile Image for Carvanz.
2,385 reviews899 followers
December 31, 2025
This book locked me in from the first page, and I loved every second of it! This author knows exactly how to hook me, and she did it again by pushing all my favorite buttons. Danger, intensity, and that delicious feeling of being not just protected, but fiercely so, by a hero who takes his job and the heroine very seriously. From the start, the tension is sharp and immediate, and I loved how quickly the story pulled me into that edge-of-your-seat mindset where I just know everything is about to go sideways.





Cass? Total alpha goodness. Controlled, watchful, lethal when necessary and utterly undone by Agnes, the woman he’s guarding. I loved the way their connection builds under pressure, where every glance feels loaded and every moment alone feels stolen. Their chemistry crackles, but it’s grounded in trust, instinct, and that quiet “I’ve got you no matter what” energy that makes my heart race. Cynthia Eden is so good at blending emotional intensity with real danger, and it works beautifully here.





By the time I finished, I was buzzing. This is romantic suspense done right. Fast-paced, emotionally charged, and deeply satisfying. This book gave me thrills, swoons, and that irresistible protector vibe I never get tired of. If you love high stakes, fierce heroes, and romance forged in fire, I highly recommend this one!

Multi POV
Safe
Triggers
Steam
Profile Image for Read All About It.
2,041 reviews23 followers
December 30, 2025
Bad guys or good guys it doesn’t matter this author writes the best alpha hero’s.

Cassius “Cass” Striker is the leader of the Night Stalkers a notorious club.

“I claimed you.” Cass extended his hand toward her. “Agnes Quinn, from here on out, you are mine.”

Agnes is a FBI agent out for revenge. She needs the help of a man she barely knows.

I think that when a real rage takes you, it’s like the devil walks on the earth.”

The past and present are about to come haunt them both in this high octane fast paced story where not everything is as it seems.

“What can I say? I like the way the flames dance.”
Profile Image for AvidReader.
1,476 reviews331 followers
January 11, 2026
Agnes Quinn surprised me in the best way! I never knew she’d this much layers and her past made me respect her more. After all that trauma, she still fought, won, helped others and become a fearless FBI agent. I loved her wicked side— a perfect match for Cass.
I already loved Cassius Striker in the previous book but in this book he was 🔥.
The plot was good and I loved how obsessed these two were with each other.
Overall a good romantic suspense.

-Fake dating.
-Forced proximity.
-MC leader x FBI agent.
-Killer on loose.
-Obsessed hero.
-TW and standalone.

I received an advance review copy and I’m leaving this review voluntarily.

Profile Image for Karen.
200 reviews5 followers
January 15, 2026
Agnes and Cass are explosive from page one. 🔥 Cass is the ultimate morally gray, touch-her-and-die protector, and he’s the perfect match for Agnes—a fierce, passionate FBI agent who will stop at nothing to bring her enemy down.

These two are combustible in the best way. They match each other beat for beat in stubbornness, loyalty, and love, and the chemistry between them is off the charts. Watching them collide, clash, and ultimately choose each other was incredibly satisfying.

I loved this entire series, and this might honestly be my favorite Cynthia Eden series so far. I’m really hoping we get Ryan and Nash next—because I’m absolutely not ready to leave this world yet.
571 reviews3 followers
January 4, 2026
I do not like the MC genre and do not read it. I only read this book because it was by Cynthia Eden. I had hoped it would be a good book, but I did not like it. It was too violent. I also think that Gray does whatever he wants. He doesn't care if it is illegal or not.

Cass may be the main male character, but he is not above killing. Agnes doesn't seem to be much better. As I said, the book is too violent for me.
Profile Image for Lea Bookjoy.
1,793 reviews89 followers
January 3, 2026
🇫🇷French & English reviews🇬🇧


*Cette chronique est basée sur un NetGalley ARC en échange d'un avis neutre et honnête*

📖Genre & Tropes📖 : Suspense romance x biker romance x grumpy x sunshine x serial killer plot x morally grey x spicy

Une romance à suspense forte en rebondissements que j’ai lu avec plaisir !!

Et je termine cette année de lecture par une de mes auteures favorites et l’un des livres que j’attendais avec le plus d’impatience : le tome de Cassius, cousin de Gray (tome précédent de la série) et biker dangereusement sexy <3

Et j’ai beaucoup apprécié ce tome ! Étonnamment, c’est Agnes qui a été mon personnage préféré ! Beaucoup de secrets, un passé très dur et des répliques qui m’ont fait beaucoup rire =D Elle était parfaite pour Cassius et j’ai adoré voir son évolution tout au long du tome et les voir tous les deux tomber amoureux ><

Bref maintenant je veux des tomes avec TOUS LES PERSONNAGES SECONDAIRES xD : Malik, les deux frères d’Agnes, le second de Cassius ...

Bref, une romance à suspense sexy et pleine de tensions à lire sans modération !

PS : to the publisher and Netgalley, thank you so much for the ARC =D

Pour plus de jolies chroniques 😘 : Mon Bujo tout en couleurs et en livres


⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐~⭐


*This review is based on a NetGalley ARC in exchange for a neutral and honest review*

A suspenseful romance full of twists and turns that I thoroughly enjoyed reading !!

And I'm ending this year of reading with one of my favorite authors and one of the books I was most eagerly anticipating : the book about Cassius, featuring Gray's cousin (from the previous book in the series) and a dangerously sexy biker <3 And I really enjoyed this book !

Surprisingly, Agnes was my favorite character ! She has so many secrets, a very difficult past, and lines that made me laugh so much =D She was perfect for Cassius, and I loved seeing her development throughout the book and watching them both fall in love ><

Now I NEED books with ALL THE SECONDARY CHARACTERS xD : Malik, Agnes's two brothers, Cassius's second-in-command …

In short, a sexy and suspenseful romance full of tension to read without moderation !

PS : To the publisher and Netgalley, thank you so much for the ARC =D

For more pretty reviews 😘: My Bujo, all in color and books
Profile Image for Sandy S.
8,284 reviews207 followers
December 30, 2025
4.5stars-WHEN HE GUARDS is the fifth instalment in Cynthia Eden’s contemporary, adult PROTECTOR AND DEFENDER romantic suspense series. This is president of the Night Strikers MC Cassius ‘Cass’ Striker, and FBI agent Agnes Quinn’s story line. WHEN HE GUARDS can be read as a stand alone without any difficulty. Any important information form the previous story lines is revealed where necessary.

NOTE: Due to the nature of the story line premise, there may be triggers for more sensitive readers.

Told from several omniscient third person perspectives including Agnes and Cass WHEN HE GUARDS follows FBI agent Agnes Quinn as she goes rogue searching for the man who destroyed her life. Believing she will find her target amongst the Night Strikers MC, Agnes goes in undercover only to discover not everything is as it appears to be. Working alongside Cass, Agnes becomes a target for who she is and what she knows, a target whose contacts are dangerous and dark. Meanwhile, Cass Striker has declared himself guardian and protector of our story line heroine, claiming Agnes as his own, a claim that doesn’t not go over very well with the Night Strikers MC.

The world building is detailed and complex as the MC find themselves at odds with one another; betrayal has been building for a very long time, and vengeance is about to place our couple in the direct line of fire.

The relationship between Cass and Agnes begins as a seduction but Cass knows immediately that Agnes is not whom she claims to be. Agnes wants to find a killer, a killer with a specific tattoo, a tattoo that continues to give Agnes nightmares and tears. Cass considers himself a monster but a monster who has fallen for our story line heroine. The $ex scenes are passionate and intense, without the use of over the top, sexually graphic language and text.

There is a large ensemble cast of questionable, secretive and dangerous secondary and supporting characters including the return of Agnes Quinn’s boss Grayson Stone (When He Defends), FBI Agent Malik; Agnes’s brother Ryan and Nash; several members of the Night Strikers MC, and a host of game players, taking aim at everyone involved.

WHEN HE GUARDS is a story of betrayal and vengeance, secrets and lies, power and control, madness and mayhem, obsession and murder, family and love. The character driven premise is action packed, detailed and dramatic; the romance is seductive; the characters are desperate and determined.

copy supplied for review
1,067 reviews11 followers
December 20, 2025
This book is deserving of far more than 5 stars. Incredible suspense entangles deranged evil with a couple intrinsically meant to fight for each other through it all. The stomach wrenching twists and turns had me biting my nails late into the night.

Agnes Quinn is done waiting for the right time. She wants answers and she wants revenge for what happened eight years ago. There is one man that can help her and walking into his biker bar might not have been the best option for an FBI agent but it certainly got his attention.

Cass Striker, leader of the Night Strikers Motorcycle Club, believes he deserves to live in darkness, undeserving of love, after all he has done. Cass has been working on infiltrating an MC group believed to be behind some brutal murders, but FBI Agent Agnes Quinn just changed the logistics of everything when she waltzed her sexy little self into his bar. He can’t believe his ears when he hears what she announces loud enough for everyone to hear.

As Agnes and Cass come to terms with their intertwined pasts that eventually brought them together they find too many coincidences that can’t be ignored. It will take trust they didn’t know they had to battle the evil enemies determined to finish what they started years ago.

I received an ARC and freely offer this review.
Profile Image for Lira.
133 reviews17 followers
Review of advance copy received from Netgalley
December 24, 2025
I loved it! When He Guards is another excellent addition to the Protector and Defender series and once again proves why Cynthia Eden is a must-read author for anyone who loves romantic suspense!

Cass and Agnes completely won me over from the very first pages. He is intense, protective, and has that irresistible dark edge; she is strong, intelligent, and far from naïve, a heroine who truly matches the hero. The chemistry between them is immediate and electric, making the book impossible to put down!

Cynthia Eden has an incredible talent for creating compelling characters with real emotional depth who pull you in from the very first minute. The relationship develops naturally, perfectly balancing romance and action.

This book is packed with action, betrayal, high tension, fun moments, and, of course, well-done sexy scenes, without ever losing focus on the story. The fast-paced plot is full of twists that constantly leave you wanting “just one more chapter.”!
For readers already following the series, this book fits seamlessly into the Protector and Defender world. For those new to it, it’s a fantastic entry point. An intense, emotional, and addictive read!

Highly recommend!

𝑰 𝒓𝒆𝒄𝒆𝒊𝒗𝒆𝒅 𝒂𝒏 𝒂𝒅𝒗𝒂𝒏𝒄𝒆 𝒄𝒐𝒑𝒚 𝒐𝒇 𝒕𝒉𝒊𝒔 𝒃𝒐𝒐𝒌 𝒊𝒏 𝒆𝒙𝒄𝒉𝒂𝒏𝒈𝒆 𝒇𝒐𝒓 𝒎𝒚 𝒉𝒐𝒏𝒆𝒔𝒕 𝒓𝒆𝒗𝒊𝒆𝒘 𝒂𝒏𝒅 𝒆𝒗𝒆𝒓𝒚 𝒘𝒐𝒓𝒅 𝒓𝒆𝒇𝒍𝒆𝒄𝒕𝒔 𝒉𝒐𝒘 𝑰 𝒕𝒓𝒖𝒍𝒚 𝒇𝒆𝒍𝒕 𝒘𝒉𝒊𝒍𝒆 𝒓𝒆𝒂𝒅𝒊𝒏𝒈 𝒊𝒕!
2,523 reviews42 followers
Review of advance copy received from Netgalley
December 29, 2025
FBI Agent Agnes Quinn is searching for a killer and she knows of only one man who can help her, MC leader, Cassius “Cass” Striker. Taking a chance, she visits him at a local bar he is known to frequent. Cass is stunned to see Agnes arrive at the bar; she has no business being there among the rough crowd. When she foils an attempt on his life, he realizes that there is much to learn about Agnes, but his only interest in her can be sexual. She aggravates him as she insists that they team up to go after the man who attacked her and her friend years ago, leaving her friend dead. Her supervisor, Grayson Stone (who bears a resemblance to Cass?), tries to intercede. He knows that Cass is on a mission to take down “The Twins”, men who kill just for the pleasure of doing so. Agnes is looking for a man with a specific tattoo, a tattoo that she remembers from the night she was attacked. Falling for Cass was not part of her plan, but as she spends time with him, their attraction can’t be contained. When her brothers, Ryan and Nash, join the hunt, will they take down “The Twins”, or will his past come back to place them in even more danger? I received an advance review copy at no cost and without obligation for an honest review. WOW, a rush from beginning to the thrilling end! (paytonpuppy)
2,556 reviews23 followers
January 3, 2026
I voluntarily reviewed a copy of "WHEN HE GUARDS" Wowzer what a journey full of danger, intrigue, twists, violence, betrayal, steam keeping you on edge.
FBI Agent Agnes Quinn has a past with Cassius aka "Cass" Striker leader of a notorious MC club in US he's been looking to take down the Twins men because they enjoy to kill& she eants his help with the killer who attacked her & killed her friend.
Cass feels like he has to protect Agnes because knowing him puts a target on her back he won't watch her die.
Agnes was pulled towards Cass when they first met, the ones who want to take down Night Strikers MC will try to use her to do it but he will protect her any cost.
Agnes will have to go undercover as Cass's woman to hunt down the bad guys it'll be interesting as they can't control themselves around each other.
Will Cass & Agnes get their HEA in the end he won't let anything happen to her, so let them try.
I was on edge with this amazing well written adventure to the end & so looking forward to the next book I loved it.
3,129 reviews
Review of advance copy received from Author
December 18, 2025
FBI agent Agnes Quinn struts into a known biker bar looking for trouble. Cass Striker is the leader of a motorcycle club and is the baddest of bads. He has a one night stand with Agnes and soon finds out that his enemies have discovered his weakness…Agnes. Agnes is going undercover to find the person who destroyed her world years ago. She has to leave the FBI and be Cass’s lady. They are on a cross country trip to a meeting and it seems Cass’s enemies are catching up to them. Cass thinks he needs to protect Agnes but she is plenty capable of protecting herself. Even when she gets kidnapped, Agnes is not taken quietly. Cass is not as dark as he thinks but Agnes sees the good in him. They are both looking for vengeance can they get it before their enemies catch up?
I loved this book!
Action.
Very Steamy.
Suspense.

* VOLUNTARILY READ AND REVIEWED FOR THE AUTHOR *
1,602 reviews13 followers
December 30, 2025
When He Guards is the 5th book in the absolutely brilliant Protector and Defender series which I didn't think could get any better. But Cass and Agnes' story for me tops the others. I just adored Agnes. Her strength, wit, humor and loyalty just jump off the pages and had me cheering so hard for her. Cass is her equal in every way. The supposed bad guy with a heart of gold and secret desire to belong. Their journey to a HEA is filled with violence and betrayal, but also with meddling family and friends. I loved the book and was hooked from the first to the last page! There were new side characters introduced who are IMO just screaming for stories of their own, so I hope the series will continue. I was fortunate to have received an early copy and am leaving this review voluntarily and honestly.
4,143 reviews21 followers
December 31, 2025
When He Guards is part of the Protector & Defender Series by Cynthia Eden. A series that I enjoyed reading. However, this time I wasn’t so sure because books with MC heroes have never been ones I have read. When I knew that Cass is Grayson Stone’s cousin from the last book, When He Defends, I thought this would be a great story. I wasn’t wrong. Cass is not nearly as bad as he thinks, nor is tough FBI agent Agnes Quinn as good as he believes. Each situation a person has to make the choice of how to act or react to the events and people in them. Past meets the present for these two while actually evil, totally evil must be stopped. Suspense galore and romance too, just the way Cynthia Eden writes them.
227 reviews1 follower
January 1, 2026
This book will keep you on your toes it is so, so good!
Thank you, thank you, thank you Cynthia Eden for writing another amazing story! This story is absolutely amazing. Cassius “Cass” Striker is a bad guy, or is he….that’s what this story will make you question. Agnes Quinn is the FBI agent that works with Gray Stone, who we met in When He Defends, and is related to Cass. Agnes has a past that she needs Cass to help her with and watching these two come together is explosive! I literally could not put this book down it is so good. Just when you think you have something figured out, Cynthia throws something new into the story line to keep you guessing. The way that Cass claims Agnes is hot and the way that Agnes defends Cass is entertaining. I loved these two together!
6,152 reviews30 followers
December 27, 2025
He's MC, she's a Fed...

When Agnes Quinn walks into an MC dive bar, she is there for one person. Cass Striker. He's an MC with a secret. He's cousin to Gray, yeah, that Gray. Fed Gray. They are like brothers. Cass is so into Agnes, the forbidden Fed with red hair and blue eyes and her sassy confidence. He will guard his enticing Fed with everything this semi bad boy's got. That includes faking it, a road trip and all the fools coming to take Agnes Quinn away from Cass. Just let 'em try. But Agnes has his six from the first and is as fearless as they come.
Highly recommend.
142 reviews2 followers
December 30, 2025
This was an excellant story: Agnes is an FBI agent tracking the man who murdered her young boyfriend and left her for dead when they were in their teens; Cass is the "undercover" head of a motorcycle club with his own agenda. Together they fight enemies as they seek justice... Agnes is a great character, funny, insightful, fearlessly brave, and personable; Cass is hard, dangerous, tough and scary! Their interactions, growing relationship and romance is touching and fun. One of my top favorites by Cynthia!
Profile Image for Melissa May.
333 reviews4 followers
January 7, 2026
When he guards by Cynthia Eden is the 5th installment in the Protector and Defender Romance series.
I read it in one sitting because I just couldn’t put it down!
It’s fast paced, suspenseful and action packed!
I absolutely loved Cass and Agnes!
The chemistry between them was amazing!
They both had the same goal, revenge on the monster from their past.
So pick up this book and read about how they achieved this goal!
You won’t be disappointed!
This is one of the best romantic suspense books I read the last year.
I received this arc from the author and this review is my honest opinion!
Profile Image for Stacy .
339 reviews2 followers
January 2, 2026
Made for a Happy New Year

This is book 5 in the Protector and Defender romance series by Cynthia Eden. I have loved every single book in this series and I was so excited to download this one as soon as it came out! I must say I did devour it yesterday and really found it delightful. Your MMC is an MC president and the FMC is an FBI agent so you immediately have drama already built in with immediate chemistry. This was a fun read and I definitely recommend it.
Profile Image for Travelogged Blogs.
1,555 reviews129 followers
January 1, 2026
This was such an entertaining read! Since the beginning, the electric chemistry between Cass & Agnes had me hooked! The twists were unpredictable and the pace was just perfect which added to the thrill! Glad I choose Cynthia Eden's book as my first read of the year, because her stories never really disappoint!
2,676 reviews2 followers
January 5, 2026
Damn!! I can't believe what happened 2 them especially toward the end. There's 2 many betrayals but not 2 fear there will b plenty of kick asses along the damn way 2 find the truth of who was behind the murder of her boyfriend and her yrs ago. Can cas find the strength 2 do the ft thing when it's needed the most? Omg!!!! I sooooooo loved it!!!!!
24 reviews
January 2, 2026
Great story!

I love the character of Agnes. I am happy you didn't make her a weak, whiny women. I like that she was brave and strong willed. I love the bad MCs. I am so happy about the great ending.
Profile Image for Cheryl A.
628 reviews2 followers
January 5, 2026
This was so so so good. I loved the suspense and mystery of this book and how Cassius and Agnes’ lives came together and changed. This was an awesome story of good overcoming the bad and evil. It had two dominant characters and I loved the dialogue between them.
Profile Image for Melissa.
767 reviews8 followers
January 4, 2026
3.5 stars

I liked this one a lot, despite the instalove. And I like the introduction of Agnes' brothers for future books.
6 reviews
Read
January 8, 2026
As always a great read. A few surprises that were unexpected. Loved the Agnes story background.
Profile Image for Christine Jalili.
2,193 reviews44 followers
Review of advance copy received from Author
December 31, 2025
I enjoyed this book. Cas really thinks he’s not good for Agnes. I loved how he ends up being so protective and possessive towards her, and even trusts her over anyone. She’s very fierce and trusts him too, believes they can be great partners even though she’s F.B.I. There’s some betrayals and could his evil uncle actually still be alive? The book will keep you on edge. Thankfully there’s a happy ever after. I voluntarily read an advanced readers copy and I recommend this book.
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