THE DROP Harry Bosch has been given three years before he must retire from the LAPD, and he wants cases more fiercely than ever. In one morning, he gets two.DNA from a 1989 rape and murder matches a 29-year-old convicted rapist. Was he an eight-year-old killer or has something gone terribly wrong in the new Regional Crime Lab? The latter possibility could compromise all of the lab's DNA cases currently in court.Then Bosch and his partner are called to a death scene fraught with internal politics. Councilman Irvin Irving's son jumped or was pushed from a window at the Chateau Marmont. Irving, Bosch's longtime nemesis, has demanded that Harry handle the investigation.Relentlessly pursuing both cases, Bosch makes two chilling discoveries: a killer operating unknown in the city for as many as three decades, and a political conspiracy that goes back into the dark history of the police department.