The detectives from Robbery-Homicide Division (RHD) who were initially assigned to the case conclude that Perez was an innocent bystander and that Elias was the target.

Despite the fact that the murders were not in Bosch's precinct, Deputy Chief of Police Irvin Irving is forced to remove RHD because many of its detectives are defendants in a case Elias was bringing to federal court.

Irving and Bosch are aware that Elias' death could inflame tensions in South Central Los Angeles, possibly leading to a repeat of the 1992 riots, especially if his killer was found to be a police officer.

Bosch suspects that he is being set up to fail by Irving after one of his rivals, Internal Affairs detective John Chastain, is assigned to help him work the case.

Bosch also finds two homeless men who report that Kincaid's body was moved to the location where it was found after Harris had already been taken into police custody.

They reveal how to gain access to a child pornography website hidden within the prostitution site's webpage, showing photos of Kincaid being sexually abused for years before her murder.

Rider believes that Stacey's stepfather is the man in the pictures; when Elias accessed this website, he set off a warning system to its administrators, possibly precipitating his murder.

Ballistics match Sheehan's gun to the weapons used to kill Elias and Perez, and the LAPD brass announce that the case is closed.

After conferring with Sheehan's superior at RHD, Bosch learns that Chastain found evidence proving that Harris was tortured but was convinced to keep quiet by Irving.

Bosch drives into a police barricade but realizes that Chastain was pulled from the backseat and is being beaten by the mob; he dies before backup arrives.

Bosch reflects that Chastain will be made out as a martyr by Irving in an effort to quell the riots, with the Angels Flight murders pinned on Sheehan, and that he will have no choice but to keep quiet in order to save his job.

Chastain is also split into two separate Internal Affairs detectives, Amy Snyder (returning from season 3) and Gabrielle Lincoln, with the rest of the task force being filled out by Robertson and Pierce.