Officer Nolan navigates building tension in his relationship with Jessica and a developing rapport with Grace while working a high-stakes criminal case involving an undercover homeland security agent. Meanwhile, Officer Chen meddles with Officer Bradford’s love life, and Officer Lopez learns some surprising news about Wesley.

Officer Nolan gets off to a rocky start after being introduced to his new training officer, Nyla Harper, who has an unconventional approach to police work after her stint as an undercover detective. Meanwhile, Officer Bradford struggles to think of an appropriate birthday gift for Rachel, and Officer Lopez finds herself navigating a case that triggers a personal memory.

An emergency alert of an impending missile attack sends Los Angeles into chaos and uncertainty, while the officers each try to keep the peace and deal with their own disasters.

Officer Nolan’s trust is tested when he tries to help the previous owner of his home reconnect with his family. Meanwhile, Officer Harper has finally earned an overnight visit with her daughter that is put into jeopardy when her past undercover life resurfaces again.

Officer Nolan is having a particularly bad day after learning his identity has been stolen and could jeopardize his position as an officer. Meanwhile, Sgt. Grey must confront his past and testify at the parole hearing of the man who shot Grey and murdered his partner.

Officers Nolan and Harper are tasked with escorting four juvenile offenders to a Scared Straight program at a correctional facility that quickly becomes a riotous situation. Meanwhile, Nolan is uncertain about his relationship with Grace after she fails to introduce him to her ex-husband.

Nolan's discovery goes much deeper than he expected and could put his life and career in jeopardy.

Ahead of Bailey's return home, John looks for clues to locate Jason Wyler. Then, Tim and Lucy swap rookies; a friendly face resurfaces at the station, and Wesley feels unsettled over Angela.

When anti-LAPD billboards emerge throughout the city, the team searches for who's responsible. Meanwhile, a car bombing prompts an investigation, Miles reconnects with an old friend, and John and Bailey assess their ability to adopt.

Documentary filmmakers interview the LAPD on a complicated missing person's case connected to John.