⭐️ ⭐️ ⭐️ ⭐️ ⭐️/5
🌶️/5

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While I do my best to make sure my reviews are spoiler-free, I may inadvertently reveal information that can help you connect plot points. So, here’s my TL;DR spoiler-free review: A solid 5-star police procedural/romantic thriller from a seasoned writer with lots of twists and turns. Do yourself a favor and read the first 4 books first.
If Lindsay Boxer and Kinsey Millhone had a love child, her name would be Kara Quinn. She is prickly, unlikeable, and works best alone. She’s also fiercely loyal, hardworking, smart, and feisty. She faces parental disappointment, but not for your typical reasons. Kara’s parents were con artists, so she did an about-face and became a cop. As an undercover agent, she’s developed few attachments outside her squad. Until her identity is leaked to the media and she’s forced to go on loan to the FBI’s Mobile Response Team under the command of Mathias “Matt” Costa. She and Matt develop a romantic relationship, and Kara learns that she can be part of a team… most of the time.
Now in The Missing Witness, Book 5 in the Quinn & Costa Series, Kara is home in LA to put an end to the human trafficking trial that changed the trajectory of her career. We pick up shortly after Seven Girls Gone. David Chen is out on bail and has placed a $1 million bounty on Kara’s head. Assistant Special Agent in Charge Bryce Thornton from the LAPD branch is still making problems with the backing of Assistant Special Agent in Charge Rebecca Chavez. Things escalate quickly when David Chen is murdered, and the only witness is a whistleblower on her way to expose a coverup within the LA Government. Violet is a computer geek with a personal connection to the growing drug and homeless crisis going on in LA. When she witnesses the murder, she disappears. Kara’s hunt for Violet leads to unexpected consequences, and forces her to confront what she thought she wanted versus what she knows she needs.
There are so many twists and turns in this book that I was actually surprised, which is hard sometimes since I’ve read so many thrillers/mysteries. I am also extremely hopeful that there will be more books in the series. Matt has a bad premonition about what will happen if James isn’t locked up for a long time.

The MRT also sees some new additions, such as FBI SA Sloane Wagner, a former Marine who goes undercover in Chavez’s office. I really hope we get to see more of her character since this book only touched on the surface. There’s also Nina Radinovich, the Assistant US Attorney and district attorney who hip-checks Chavez when she gets pushy about Kara’s alibi for Chen’s murder. You can just tell she’s a badass and I hope we get more of her. Brennan’s writing is so layered, and the story is so well-constructed that this was hard to put down.
While the story is billed as a romantic thriller, I would call it more of a police professional thriller with a side of romance. Matt and Kara‘s relationship is the absolute definition of a slow burn. And while I give it 1.5 spicy peppers for a heat reading, it’s pretty tame as far as a romance novel goes.
All in all, I love, love, loved this book! It’s no secret that police romance books are my absolute favorite, especially if they have multiple agencies and offices. I feel like I should know these characters (Lex?) from her other books, but honestly, it’s been so long since I read them that I can’t remember. Maybe at some point I’ll get to go back and re-read them.
Here’s hoping for more books in the Quinn & Costa series.
Thank you so much to the author, Allison Brennan, Netgalley and Harlequin Trade Publishing for the ARC copy of this book. The Missing Witness is out now! You can grab your copy here.
Other title in the Quinn & Costa Series:
- Book One: The Third to Die
- Book Two: Tell No Lies
- Book Three: The Wrong Victim
- Book Four: Seven Girls Gone
- Book Five: The Missing Witness

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