Dunne Diehl Mysteries Books in Order

The Dunne Diehl Mysteries are comic mysteries written by Becky Clark and Ted Hardwick. The books center on Cassidy Dunne and her longtime college friend Dan Diehl, two middle-aged best friends with a long shared history, plenty of sharp banter, and a habit of being pulled toward trouble.

Cassidy is not a conventional sleuth. She is a fifty-something woman with a secret candy stash, a lingering connection to her ex-husband, and a talent for turning a bad idea into a bigger one. Dan has been there for many of those ideas over the years. Their friendship is the backbone of the series, and it gives the books their quick, conversational energy.

Cassidy has baggage. So does everyone else.

In Banana Bamboozle, Cassidy has one too many of the title cocktails at a backyard party and becomes certain that she has seen her niece. The problem is that the niece died as an infant fourteen years earlier. Dan initially assumes Cassidy's judgment is impaired, but Cassidy cannot let the resemblance go. As she chases the truth, old relationships, family pain, and a problem that could damage Dan's reputation make the search more personal and more risky.

The mystery is driven by Cassidy's refusal to leave a question alone. She can be impulsive and not especially prudent, but she is also loyal. What begins as a strange sighting grows into a puzzle with serious consequences for people she cares about.

Marshmallow Mayhem keeps Cassidy and Dan together but changes the setting and the pressures. Cassidy hopes for a winter RV trip with family, friends, and campfire treats. Instead, the journey brings creepy locals, long-running feuds, suspicious circumstances, and a dead body. The clues point uncomfortably close to Cassidy, forcing her to figure out what happened before the trouble settles on her for good.

These are light-footed mysteries, but the characters' personal histories still matter. Cassidy's tendency to joke, snack, and barrel forward does not erase the grief and complications underneath. Dan is not just a sidekick, either. His history with Cassidy means he knows both her better qualities and the exact ways she can make a situation worse.

The books lean into friendship, family secrets, romantic awkwardness, and humor that can turn a tense moment sideways.

Readers should expect a cozy mystery tone with adult characters, offbeat situations, and a central partnership that feels lived-in. Start with Banana Bamboozle, which introduces Cassidy and Dan's history, then continue with Marshmallow Mayhem for another case built around their stubborn loyalty to each other.