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.

Lydia and her partner, Detective Russell Clarke, investigate a string of jewelry thefts in Bel Air and Ben discovers one of the victims is someone he knows. In another matter, Ben must face his past when it comes back to haunt him. Meanwhile, John reveals a secret he's been harboring for a long time, Russell has troubles at home, and Sammy and Nate take extraordinary steps to protect their eyewitness, Janilla, after another attempt is made on her life.

When Sammy discovers Marta has made bail, and fearing another attempt will be made on Janilla's life, he arranges to have her stay with Lydia, but Janilla's safety is compromised after she visits her old neighborhood. Meanwhile, Sal continues to spy on his daughter's activities, Dewey flips out when Chickie confronts him about his drinking problem, and Russell is caught in the middle when he attempts to defuse an ongoing domestic battle between a neighbor and his wife.

Lydia and her new partner, Detective Rene Cordero, investigate the disappearance of an elderly man. Meanwhile, Nate and Sammy investigate a freeway shooting and inadvertently threaten the integrity of a major undercover operation. Elsewhere, Chickie finds herself in the middle of a mini-riot after her new partner panics and takes a shot at a 13-year-old boy.

Lydia and Rene are called to Compton to investigate the murder of a young SULA student, only to discover that the girl was not exactly who her parents claimed she was. Meanwhile, John takes Ben with him to Indian Wells to attend the funeral of his friend, a cop who committed suicide. On the way back, they stop at the rehab center to check in on Dewey.

John, Ben, and Chickie are sent out as part of a maximum deployment to capture the “Canyon Rapist,” a perp who's been impersonating a cop. Russell is back, but on light duty as he continues to struggle with his recovery after being shot. While working a double-homicide with his old partner, Lydia, he discovers he's no longer up for the job. Sal plans a special night out to commemorate his wife's promotion, but their evening is ruined when their daughter reveals Sal’s affair with TV news reporter Mia Sanchez. Chickie gets a chance to prove to herself -- and others -- that she still has what it takes to be a good cop.

When a rape victim hires a lawyer and refuses to talk with the two detectives unless her lawyer is present, Lydia and Josie want to know why. Meanwhile, John strikes up an unlikely friendship with a boy who returned home after a sleepover, only to discover his parents had packed up and moved during the night, abandoning him and leaving him to fend for himself, Later on, John begins to feel the stress over the prospect of testifying at his father's upcoming parole board hearing, but he doesn't realize his testifying will open up an emotional can of worms that he's not prepared for.

While working a celebrity murder, Lydia discovers the pros and cons of being in the spotlight. Meanwhile, six weeks after Nate's murder, Sammy finally returns to street patrol. Elsewhere, John voices his anger over the department's waste of money, man-power, and hours spent guarding the home of a celebrity suspected of murdering his estranged wife from the reporters trying to get a scoop.

When crime scene photos from the case of the celebrity suspected of murdering his estranged wife show up on the internet, all of the first responders are suspended, including Lydia and Josie. Further investigation proves the photos were the unauthorized pictures taken by Lydia using her phone, and she's shocked when she learns who was responsible for the leak. Meanwhile, Sammy fails to pick the right guy from the line-up for Nate's murderer, and Dewey and Chickie are involved in a high-speed chase that ends in disaster.

Lydia dons a uniform and hits the streets when the shift is short a supervisor and she must fill in. Meanwhile, John and Jessica are stuck with a film crew tagging along on their calls. Elsewhere, Ben infuriates Sammy when he implies Sammy planted evidence.

Jessica and John exchange angry words after she lies to Internal Affairs about the facts surrounding her shooting of a teen with a toy. Meanwhile, Sammy continues to hold a grudge with Ben and Lydia continues to dodge questions about her condition.

It's the last day on patrol for Tang, as she prepares to move to another precinct as sergeant. But first she wants to tie up some loose ends on the beat. Lydia is pressured to make a decision about the extent of her police duties during the rest of her pregnancy. With Sammy recovering from injuries, Ben and Dewey are partnered together. But Ben is bent on tracking down the prostitute he's been trying to help and then getting her and her daughter away from the abusive pimp controlling their lives.

John is forced to think about what life will hold for him once he leaves the LAPD. Lydia connects with a man she sent to death row earlier in her career. Much to his chagrin, Sammy becomes a tabloid celebrity for the day after a very public act of heroism. Ben makes a dubious decision to get a drug dealer arrested. And a foot pursuit puts Dewey in danger.