LAPD detective Harry Bosch is a loner and a nighthawk. One Sunday he gets a call-out on his pager. A body has been found in a drainage tunnel off Mulholland Drive, Hollywood. At first sight, it looks like a routine drug overdose, but the one new puncture wound amid the scars of old tracks leaves Bosch unconvinced.

To make matters worse, Harry Bosch recognises the victim. Billy Meadows was a fellow 'tunnel rat' in Vietnam, running against the Viet Cong and the fear they all used to call the Black Echo. Haunted by the memory of failing Billy Meadows, Bosch is determined to succeed in bringing his killer to justice.