This 10th Harry Bosch novel links the retired LA cop with characters from previous non-Bosch novels. A serial killer and ex-FBI agent named Robert Backus, the title character from Michael Connellys first novel, THE POET, was commonly thought to be dead. But now the Poet has resurfaced and has started killing again. At risk is FBI agent Rachel Walling, a former protégé of Backus who subsequently investigated his first killing spree. As she begins a new hunt for the Poet, her path crosses that of Harry Bosch, who believes that the natural-seeming death of a friend, Terry McCaleb (a character from Connellys BLOOD WORK and A DARKNESS MORE THAN NIGHT), may actually have been one of the Poets murders.