A young Jane Doe found murdered in an alley sets Lydia on an emotional journey, and she discovers her suspect was involved in a cold case. Meanwhile, Sammy's wife, Tammi, decides to embark on a new career, and Nate deals with some family issues and reveals a deep secret.

In an effort to recover Detective Daniel "Sal" Salinger's stolen weapon, Sammy and Nate crack down on the residents in the neighborhood where it occurred. Elsewhere, a man exposes himself to Lydia.

Ben learns the hard way, some valuable lessons about the importance of following established procedure and protocol, Lydia's current murder investigation takes an unexpected turn, and Nate and Sammy are unprepared when a group of people they encounter turns into a violent mob.

Jessica goes the extra mile to assist a homeless war vet obtain an ID so he can be admitted into a shelter . Meanwhile, Sammy is determined to save a dog after he accidentally shoots it in the leg. Elsewhere, Lydia struggles with a serious personal matter while she and Ruben investigate the murder of a man who sheltered and aided women in need.

Lydia and Ruben investigate the death of a young nanny, but first they have to find the kids who were in her care. Ben tries to intervene in the life of a prostitute with a daughter, but his efforts only make things worse. Tang gets an update about the boy she shot, but John still wants her to come clean about what really happened.

Officer John Cooper clashes with his new boot, Gary Steele, a vet from Afghanistan. Lydia struggles to balance detective work and motherhood. Ben Sherman falls in with a sketchy crowd of cops, while Sammy Bryant is trapped in a hellish custody battle with Tammi.

After Mendoza is injured in a drive-by, Ben takes it upon himself to solve the case, much to Sammy's dismay. Lydia regains her footing as a detective while investigating the murder of a female boxer's husband. Tensions between Cooper and Steele finally come to a head during a traffic stop-gone-sideways.