After three years out of the LAPD, Harry Bosch returns, to find the department a different place from the one he left. A new Police Chief has been brought over from New York to give the place a thorough clean up from top to bottom. Working with his former partner, Kiz Rider, Harry is assigned to the department's Open-Unsolved Unit, working on the thousands of cold cases that haunt the LAPD's files. These detectives are the Closers - they put a shovel in the dirt and turn over the past. By applying new techniques to old evidence they aim to unearth some hidden killers and bring them to justice, for 'a city that forgets its murder victims is a city lost.'
Harry and Kiz are given a politically sensitive case when a DNA match connects a white supremacist to the 1988 murder of Rebecca Verloren, a sixteen-year-old girl. Becky was of mixed race, and the case appears to have a racial angle. This was LA before the riots and Rodney King; the city was a powder keg waiting for a match. The detectives who worked the case all those years ago seem to have done a decent job, but something doesn't fit. Meanwhile Harry's nemesis, Deputy Chief Irving, is watching him. In the new 'clean' LAPD Irving has been sidelined to a meaningless job. Compelled by vengeance, he hopes that Harry will make a slip.