Casualties

The officers grapple with the aftermath of a plotted attack on the city of Los Angeles, leaving Bradford fighting for his life.

Nolan teams up with new night detective Pablo Armstrong for a murder investigation case that results in an unexpected reunion with a former love interest.

Officer Nolan navigates his relationship with Jessica and a developing rapport with Grace while working a high-stakes criminal case involving an undercover homeland security agent; Officer Chen meddles with Officer Bradford's love life.

Officer Nolan gets off to a rocky start after being introduced to his new training officer; Officer Bradford struggles to think of an appropriate birthday gift for Rachel; Officer Lopez finds herself navigating a case that triggers a personal memory.

The rookies are asked to develop their first confidential informants; Officer Chen's mother complicates her home life when she comes to stay with her.

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.

John and Jessica's relationship gets a lot more complicated after she delivers some surprising news; Officer Bradford and Officer West are assigned a community policing project helping out the Watts Rams as volunteer coaches.

Officer Nolan kicks off his birthday by babysitting a crime scene at a law office; Officer Bradford and Officer West are set to receive special awards; Sgt. Grey rides patrol with Officer Harper after she requests an early annual evaluation.

Officer Nolan's trust is tested when he tries to help the previous owner of his home reconnect with his family; Officer Harper's overnight visit with her daughter is put into jeopardy when her past undercover life resurfaces again.

Officer Nolan and the team are charged with escorting a notorious female serial killer to the graves of her victims; Officer Chen meets a seemingly perfect man who sparks her interest; Officer Lopez worries about Wesley.

Officer Nolan and the entire team are in a desperate search to rescue Officer Chen after her abduction; Officer Lopez discovers Wesley unconscious from a dangerous cocktail of alcohol and pills.

Nolan takes his son's fiancée, Abigail, on a ride-along after she shows interest in becoming a police officer; Jackson's relationship becomes increasingly complicated.

Nolan is given some life-changing news and invites Grace over for a home-cooked meal in his newly remodeled kitchen; each unit is tasked with following up on dormant cases in hopes of uncovering new leads.

Officers Nolan and Harper investigate a murder which may have national security implications; Officer Bradford must confront his past when he crosses paths with a homeless veteran.

Officer Nolan learns his identity has been stolen and could jeopardize his position as an officer; Sgt. Grey must testify at the parole hearing of the man who shot him and murdered his partner.

Officers Chen and Bradford respond to a call at the Los Angeles auditions of "American Idol" and Officer Chen ends up facing Ryan Seacrest and the judges; Chen befriends a reporter whose motives are not clear.

Officer Nolan's relationship with his first confidential informant is tested when he discovers her back on the street dealing drugs; Lucy's fear of dating following her abduction is beginning to threaten her friendship with Jackson.

Officers Nolan and Harper escort four juvenile offenders to a Scared Straight program at a correctional facility, but it quickly becomes a riotous situation; Nolan is uncertain about Grace after she fails to introduce him to her ex-husband.

Officers Nolan, Chen and West are squeezed harder than ever before as their training officers evaluate whether they are truly ready for the job; one of the rookie classmates is involved in a shooting.

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