While Brooklyn has temporarily relocated to her parents' place in Sonoma, she attends an excavation of the caves hidden deep under their commune. A room is unearthed, revealing artwork, rare books, cases of wine, a chest of jewelry...and a perfectly mummified body. A closer examination of the murdered man's possessions reveals a valuable first edition of Jules Verne's A Journey to the Center of the Earth containing a secret treasure map.

Word of the explosive find draws in reporters, art appraisers, and questions. After a new presence threatens the town's peace, it's clear that not all crime is buried in the past. So Brooklyn decides to do a little excavating of her own and solve the mystery of the treasure before anyone else is written off...