As Commander Sharon Raydor and her squad track down the lethal perpetrators, they face additional challenges from a new boss, Assistant Chief Leo Mason, whose methods force them to question their faith in the justice system and their ability to grapple with changing priorities. Finally, the squad must negotiate elements of extreme risk as they confront the return of a familiar serial rapist.

Smart, suspenseful and marked by moments of love and loss, these last 12 episodes charge from one cliff-hanger to the next, culminating in an explosive, emotional climax that underscores the detectives' uncompromising dedication to their work, their colleagues and the people of Los Angeles.