Mickey Haller got a wrongfully convicted man out of prison, whom Ballard encountered during the investigation of a serial killer case. This success brought Mickey not only fame and money but also a desire to help the innocent in prison. He hired his stepbrother, former detective Harry Bosch, and tasked him with ‘finding a needle in a haystack,’ that is, examining the letters sent to Haller by allegedly wrongfully convicted prisoners. And when someone like that appears, Mickey uses all his skills as a great lawyer to get them out of prison hell and back into normal life.