When a prison bus crashes, all units must respond as some inmates face severe injuries while others seek an opportunity to flee. In the wake of the accident, Officer Nolan tries to impress an FBI hostage negotiator while tracking down an escaped convict.

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.

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.

Officer Nolan, Officer Harper and Detective Lopez are assigned to the kidnapping of the son of a criminal court judge who has a long list of enemies who could possibly be involved.

Now that John Nolan knows about Bailey’s past, he must decide if they still have a future. Meanwhile, when a plane crashes in the middle of the city the team races to find out why.

The team must rely on a criminal for his expertise to help take down an even bigger threat. Meanwhile, Officers Chen and Bradford investigate the murder of an unhoused teenager who used to be friends with Tamara.

Nolan and Celina must stand guard at a hospital after a dangerous prisoner needs surgery. Aaron, Lopez and Harper look into a string of robberies. Tim and Lucy consider how their secret relationship will affect their work. Lopez gets unexpected news.

The team comes together to celebrate John and Bailey’s wedding; meanwhile, Celina discovers a discrepancy in her case, leading to a new discovery. Elsewhere, Lucy and Tim’s relationship is put to the test.