Treasure Hunt by John Lescroart (2010)
Wyatt Hunt’s detective agency is in a slump. Just as he’s considering closing the doors, his only employee Mickey Dade stumbles across the body of Dominic Como, the head of a network of social service agencies with a $50 million budget.
Mickey envisions a scenario where Hunt’s agency would act as a clearinghouse for tips to be filtered to the police, partly to prove the innocence of Alicia Thorpe, the sister of his culinary school friend. As the investigation moves forward, the sinister side of philanthropy produces several motives and suspects, as does the romantic entanglements and resulting jealousies.
Mickey’s sister and grandfather join Dade and Hunt in their search for the killer and each struggles to figure out who they can believe. The police have one theory, Dade has another and Hunt wonders whether other recent events have skewed his ability to trust. The tension thickens as more killings occur and people close to the investigation disappear.