Coyote Hills by Jonathan and Jesse Kellerman

Clay Edison has left behind the Alameda County coroner’s office to strike out on his own as a private investigator. He’s perfectly happy investigating calm, low-stakes embezzlement cases - that is, until PI Regina Klein calls him with a case only he can solve. Adam Valois, the missing son of a wealthy Los Gatos couple, was found floating dead in the Bay with a head injury and drugs in his system. The police have lost interest, ruling it a likely overdose. But as Clay digs deeper into Adam’s mysterious death, he begins to suspect darker forces are at play...