Back when Harry Bosch was just a rookie homicide detective, he had a mentor who taught him to take the work personally and light the fire of relentlessness for every case. Now that mentor, John Jack Thompson, is dead, and his widow gives Bosch a murder book he took with him when he left the LAPD twenty years before - the unsolved killing of a troubled young man ... Harry Bosch and LAPD Detective Renée Ballard come together again on the murder case that obsessed Bosch's mentor.