The Golem of Paris by Jonathan Kellerman

From two #1 bestselling masters of crime fiction comes an extraordinary thriller about family, murder, and secrets.

It's been more than a year since LAPD detective Jacob Lev learned the remarkable truth about his family, and he's not coping well. He's back to drinking, the LAPD Special Projects Department continues to shadow him, and the memory of a woman named Mai haunts him. And while Jacob has tried to build a bridge to his mother, she remains imprisoned inside her own tattered mind. Then he comes across the file for a gruesome unsolved murder that brings the two halves of his life into startling collision. Finding the killer will take him halfway around the world, to Paris. It's a dangerous search for truth that plunges him into the past. And for Jacob Lev, there is no place more frightening.