When mysterious remains are found beneath the local playground and foul play is suspected, Coop jumps to solve the case.

The morning human bones turned up buried beneath the slide in the old playground, Coop was busy helping his mom at her café and bookstore, A Latté Books. Coop can't wait to discover the details about what the police have found.

But then the facts hit too close to home: the remains belong to his grandmother who supposedly left town some forty years ago. Folks thought she got bored with Windy Bottom, but it looks like something much more sinister happened.

When the police pinpoint Coop's Gramps as the main suspect, Coop and his pals, Justice and Liberty, begin their own investigation. Coop's convinced the person responsible is any one of a number of eccentric residents of Windy Bottom. The police and Coop's mother tell him to cease his detective work, but that only fuels Coop's search to uncover the truth.