The golden years are tainted red with murder on Spartina Island.

When Courtney Evanson's body is found in the dunes of Spartina Island, the peaceful facade of the retirement haven is shattered. Retired detective Sean Tanner teams up with Detective Sergeant Charlie Nash, diving into a case that's far more twisted than they imagined.

A stolen credit card initially offers a promising lead, but when their main suspect turns up dead, all their theories unravel. The investigation grinds to a halt—until The Mudflats Murder Club uncovers a crucial piece of evidence: a ruby pendant hidden in the pocket of the clothes Courtney was wearing when she died. This pendant is more than a simple find—it's the unmistakable link to a 27-year-old cold case involving another young woman's violent death.

The deeper they probe into the case, the more Sean's team unearths, including secrets about Charlie's father, who mysteriously disappeared a decade ago. As the lines between past and present blur, Sean must navigate these buried truths without losing Charlie's trust.

As the body count climbs and three seemingly separate cases collide, the stakes on Spartina Island have never been higher. The Cordgrass Killer is still out there—watching, waiting—and Sean and Charlie's relentless digging has put them squarely in the crosshairs. Can Sean and Charlie outpace a killer who's always a step ahead…or will the sands of Spartina Island claim them next?

Brian Thiem, drawing from his experience as a former detective and cold case investigator, crafts a suspenseful story perfect for fans of Richard Osman's Thursday Murder Club and Only Murders in the Building. Dive into Spartina Island's dark underbelly, where retirement dreams turn into deadly nightmares, and age is just a number in the pursuit of justice.