I loved Tess Gerritsen’s “The Spy Coast,” and her sequel, “The Summer Guests” makes this a series that is sure to be one of my favorites. There’s so much to enjoy—especially for readers of a certain age. We love reading about main characters who are our (Boomer) age. Main characters whose aches and pains might be there, but don’t stop us from enjoying life and doing our best to be active and actively participants in the world around us.

The main characters in this series are a group of retired CIA agents who live in the small town of Purity, Maine. There they meet for drinks and call their group the “Martini Club,” as they meet to ostensibly discuss books, but really to enjoy drinks and the company. In this novel, a the daughter of a family who has a summer home on the shore of Maiden Pond, disappears. She was last seen with the granddaughter of Maggie Bird’s neighbor, Luther. Maggie is one of the group of senior spooks, and she knows Luther. She doesn’t believe he was involved in the disappearance, and she is determined to help get to the bottom of the mystery.

Another character is that of Jo Thibodeau, the acting chief of police. She’s young, but she’s smart and effective. She doesn’t appreciate the help of the Martini Club, but her feelings change over the course of the novel. It’s enjoyable to see how the relationship between Jo and the members of the club changes over the course of the first book and this one.

The plot is complex and the missing girl is the stepdaughter of Ethan Conover. The Conovers are a wealthy family who have summered in Purity for decades. But there is mystery surrounding this family and their neighbors, two other families who bought their homes at the same time as the Conovers, all of whom are very friendly with each other. It quickly becomes obvious that these families have something to hide.

And when the bones of a young woman are found on the bottom of the pond, near the Conover’s house, the suspense deepens. What role does local Reuben Tarkin, whose father killed four people fifty years before, play in this? Susan Conover, Ethan’s wife of two years, isn’t sure who she can trust, but she’s desperate to find her daughter.

Gerritsen’s brilliant plotting creates a novel that is filled with nonstop action, multiple suspects and enough suspense to keep us reading and turning the pages to see what the senior sleuths and their young counterpart, Jo, will unearth next. There is a surprising twist at the end; actually, more than one surprising twist as I was also surprised at how the perpetrator was finally unmasked. But make no mistake, there’s a reason this series is currently in development for a TV series. It’s filled with great characters, hair-raising scenes, and a picturesque setting. Put this one at the top of your summer reading list.

Please note, this review is based on the finished hardcover book provided by the publisher.