FBI agent Rachel Walling finally gets the call she's dreaded for years: the one that tells her the Poet has returned. Years earlier she worked on the famous case tracking down the serial killer who wove lines of poetry into his hideous crimes. Rachel has never forgotten the killer who called himself the Poet - and apparently neither has he. Harry Bosch gets a call, too. The former LAPD detective hears from an old friend whose husband recently died. The death appeared natural, but this man's ties to the hunt for the Poet make Harry dig deep - and lead him into a terrifying and unknown world.