Death by Diamond Lab: A Hilarious Feel-Good Cozy Mystery

by Tess Marlowe

A vanished boyfriend, a high-end "gift" from a Labrador, and a clairvoyant parrot.

When retired army therapist Alex agrees to help a frazzled newcomer find her missing boyfriend—and his missing dog—she expects drama, not a full-blown conspiracy. But after the Labrador drops a diamond under the bush and the boyfriend washes up dead, Alex and her husband Reg (a dry-witted ex-SEAL with excellent aim and zero patience) realize their paradise comes with a body count.

With their retired bomb-sniffing dog, Bombay, leading the way, the couple uncovers a smuggling ring using dogs to move diamonds across the border. But the deeper they dig, the messier it gets—shady cops, secret wives, and a jewelry store with gang ties. And at the center of it all? A mysterious woman who’ll stop at nothing to protect her empire.

To crack the case, they’ll need sharp instincts, stronger cocktails, and a dog who’s hell-bent on unretiring.

Welcome to San Malvino. Pack sunscreen and an arrest warrant.

Genres: Cozy Mystery

82 pages, Kindle Edition

Published June 9, 2025

Reviews

[Connie]

This book is hilarious! And the dog doesn't die like in most books with a dog.

[Louise Bray]

This was really fun. It's set on some sort of tropical island, and the vibes were immaculate - it was so easy to picture this cheap-ish but fancy-ish holiday resort that I'm sure many people have visited at some point. Our main characters are retired Alex and Reg. A new woman, Shannon, shows up on the island in quite a state, as her boyfriend and dog have vanished. Alex and Reg agree to help her figure out what's really happened to them.

It was really easy to read, funny in parts, and very cosy. The mystery itself wasn't the best and I feel like there were a lot of plot holes. I don't think an 80-page mystery is ever going to be very complicated, but I think the ending could have been a bit more satisfying.

A fun quick read nonetheless and I want to continue with the series - hopefully the writing improves with each instalment.

[Tambi Smith]

If you've ever been curious about what happens when a seasoned Navy SEAL and an Army therapist retire to a tropical paradise, Death by Diamond Lab is your answer. Spoiler: they spend much less time relaxing in hammocks than you might expect. As the first installment in the Island Whodunnit series, Tess Marlowe introduces a refreshing mix of sun-soaked atmosphere and gripping mystery.

There seems to be trouble in paradise. The story follows Alex and Reg, a retired Army therapist and a former Navy SEAL, who plan to enjoy a tranquil retirement on the whimsical Caribbean island of San Malvino. Their serenity is quickly shattered when a frantic newcomer seeks their help to find her missing boyfriend and his dog. What begins as a simple search quickly unfolds into a complex conspiracy involving a mysterious diamond and a body on the shore. Marlowe masterfully captures the leisurely "island time" vibe with vivid depictions of the locals and the humid breeze, all while weaving a high-stakes plot of missing persons and hidden gems.

The Characters are expertly well-developed. The core of the story is the partnership between Reg and Alex. Unlike typical amateur sleuths, these two are seasoned professionals whose witty, affectionate banter is rooted in years of marriage. Their teamwork is seamless, reminiscent of the sharp chemistry between Castle and Beckett (one of my favorite duos). The supporting cast adds a layer of "found family" charm to the adventure. I truly appreciate how Shannon’s character was crafted. She is depicted as being clearly overwhelmed by her situation and lacks the "island survival" skills that both the locals and the main duo have, illustrating her as someone who is in over their head. While the animals in the story are real scene stealers. Bombay, their retired bomb-sniffing dog, who eagerly returns to work is as an integral part of the investigative team as Alex and Reg. Then there is Polly, a "clairvoyant" parrot who provides loud, colorful, and often hilarious commentary.

Death by Diamond Lab is an outstanding start to a series for those who enjoy tropical mysteries featuring competent adult protagonists rather than "accidental" detectives, sprinkled with humor. The book's pacing is brisk, with no unnecessary filler, making it an ideal choice for a quick weekend read or a beach getaway. Tess Marlowe's writing is clean and dialogue-focused, ensuring the mystery is easy to follow yet filled with urgency. The action-packed ending is both satisfying and packed with unexpected twists. It is a lively read that left me eager to dive into the next adventure with Alex, Reg, and Bombay - Death by Hibiscus Bush.

I highly recommend this book for fans of Fans of Castle, retirement-age "power couples," and anyone in need of a brief, delightful, and humorous literary escape. Don't miss the wave—this mystery is a real gem!

[Shelley Vlajnic]

I discovered this series of novellas while reading Tess Marlowe's second series, A Good Year for Bad Decisions (highly recommend). The Island Whodunnit series is so fun and I can't put them down. I started reading them last week and I'm about to start #15 in the series. They go really fast since they are short. The characters are fun and their stories keep building as you move from one to the next. Each novella is a standalone story, but I recommend reading them in order since you'll get to know the main characters more, and some of the supporting characters show up repeatedly. I am thoroughly enjoying a cozy mystery escape to the Antilles, and will be finishing this series soon. I hope Tess keeps releasing more! They are well-written, funny, move fast, and just overall a great read.

[Tari]

I absolutely loved Alex and Reg’s characters and once I barely got into the book realized they couldn’t be more like Beckett and Castle from TV if the book was actually written about those two, lol. It made the reading even more enjoyable picturing two of my favorite TV cop show characters. The banter, the dialogue—everything was spot on and hilarious when it needed to be. Bombay was the goodest doggie ever and being a retired bomb sniffer, he managed to help the showdown progress without incident. I’ve already borrowed the next in series and can’t wait to read it!

[Whitney Marie]

I think with more development this could have been a five star book! (It’s closer to a novella) I loved the humor and the dialogue between the main two older sleuths. I also loved the animals & wish they would have had more screen time/development. There were a couple of typos that I caught. Overall this was a cute & lighthearted mystery that I enjoyed my time with. I do wish there would have been more action surrounding the final reveal. There is also some mild and infrequent language but otherwise it is clean! This has potential and I hope the author will continue to improve on it.

[Dallass]

Short but fast paced and intriguing. I enjoyed the tropical island setting with the quirky locals, and the mystery of the disappearing boyfriend and little Labrador. Even though the cover suggests a cozy mystery vibe, I won't class as such. Not your average amateur unskilled busybodies investigating, that's for sure. Liked this enough to pick up the second book... well, at least add it to my list to pick up soon.

3.5 stars

[Robyn]

Retirement busted

Alex, Reg and Bombay are enjoyment when Shannon shows up looking for heNr boyfriend and his dog. They decide to help her move into her boyfriend's place but she doesn't know any Spanish. Reg and Alex help her. Using their former skills they start looking into what is going on. Good story enjoyed the characters.

[Celest]

My First Tess Marlow

This is a really fun mystery. The characters are a little different and some can't be trusted. Others will save your life. I'm happy that I found this intriguing story.

[Stephanie K.]

Cute mystery

death by diamond is a fast, cute mystery. Nice characters. It is a good beach read , not deep, so u can be interrupted and not lose track of the plot. Thanks. I will buy another in the series.

[Elizabeth Hubbell]

Loco and Loud Parrot

Great novella, bad editing. This was a good detective story, great beginning tale of Alexandra and Reg, the detective duo on a beach island and Bombay, faithful K9. Can't wait to read the other's, hopefully learn more backstory.

[Candis]

Quick Cleanser

New to me author and I wasn't disappointed. I'll be using this author Tess, for any future change of pace reading. The book itself was a quick but efficient read. It's what I consider a palette cleanser with simple action and mystery.

[Paula]

Short and sweet

Great characters, fast paced, good dialogue. Just wish it hadn’t been so short. Good book for when you want a good, quick read and not stay up all night finishing it. I will definitely be reading a few more.

[Jamie Merritt]

I would probably rate this 3.75 if it was a different rating system. Cute fast paced mystery. Looking forward to how this series develops over the next few stories. I am definitely becoming a fan of Tess Marlowe and her short story series.

[L. Stone]

This is exactly what the subtitle promises: a hilarious, feel-good read. It's the perfect pick-me-up when you need something uplifting.

[Jemma]

I love this series, excellent reading!

[Lee Brothers]

It was a quick book but it was fun to read. I really liked Bombay, Alex and Reg. I hope there's more to come.

[Kimberly McCormick]

Interesting quick read

I read it in under an hour and enjoyed it immensely. Good story with an interesting mystery and colorful characters. Can't wait to read more in the series.

[Kirsten]

This was kind of fun

[Josey Fansher]

Fun!

Fun and super cute short story. As a dog lover, enjoy the dog plot and no dogs harmed! Excited to continue the series.

[Erna Van]

Death by Diamond

A lovely mystery. The characters are interesting. Lots of action, mystery and drama. A nice way to relax and leave the real world behind for a while.

[Elizabeth Hughes]

A super fun read with characters I look forward to spending more time with.

[Mary Ann]

cute short mystery

I thought the title was fun, so I borrowed the book. It was well worth the read. Going to borrow the rest of the series.

[Armen]

Gifted author. Death by Diamond Lab is a delightful island escape packed with quirky characters, clever twists, and laugh-out-loud moments. I couldn’t put it down!