Officer John Cooper returns to duty after recovering from back surgery and meets his new partner, Officer Jessica Tang, a tough and disciplined cop with her own set of baggage from working the streets. Lydia, whose new partner is Ruben Robinson, can't seem to escape helping a former CI who won't stay in safety. Ben, Sammy and Dewey chase an armed man into an elementary school, while Ben bumps heads with an intense street cop whose cynical attitude is affecting their work.
Ben Sherman is about to complete Phase 2 of his rookie year. During Phase 3, he will be allowed to patrol solo. Detective Adams and Officer Brown are assigned new partners. Rene Cordero, Adams's new partner, is obsessed with receiving glory and press coverage. Their first case involves the search for an elderly man who left his home accompanied by an unknown black man. Brown's new partner, Slug Ferguson, quickly demonstrates how he earned that nickname when he starts a riot during a traffic stop. Meanwhile, Detectives Moretta and Bryant investigate a Sonora shootout involving a young Mexican man shot dead while driving an unregistered Bentley.
