Nolan teams up with new night detective Nick Armstrong for a murder investigation case that results in an unexpected reunion with a former love interest. Officer Bradford reluctantly accepts help from Officer Chen as he prepares for his sergeant exam, and Officer West pursues an unconventional move after finding himself in need of a new home.

As part of their second phase of training, the rookies are asked to develop their first confidential informants. Officer Nolan soon discovers that no two informants are the same and struggles with his newest task. Meanwhile, Officer Chen’s mother complicates her home life when she comes to stay with her.

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

Officer Nolan and the entire team are in a desperate search to rescue Officer Chen after her abduction and must attempt to get Rosalind to help them in their search. Meanwhile, after Officer Lopez discovers Wesley unconscious from a dangerous cocktail of alcohol and pills, she is forced to keep him close by.

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

Officer Nolan’s relationship with his first confidential informant is tested when he discovers her back on the street dealing drugs. Meanwhile, Lucy’s fear of dating following her abduction and her intrusion into Jackson’s relationship is beginning to threaten their friendship.

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

Officer John Nolan and Officer Nyla Harper are assigned to a community policing center to help rebuild their station’s reputation in the community. Nolan is determined to make a positive impact but Nyla has her doubts.

Officer Nolan is taken hostage by a man with nothing to lose while the station goes on lockdown and races to identify the suspect before time runs out. Meanwhile, Officer Jackson and his training officer, Officer Doug Stanton, reach a tipping point in their relationship that could end Jackson’s career.

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.