Officer John Nolan is once again face-to-face with serial killer Rosalind Dyer. Officers Bradford and Chen work undercover with Detective Lopez and the Las Vegas Police Department to arrest leaders of a major criminal enterprise.

Officer John Nolan is moving closer to his new role as a training officer. Meanwhile, Lucy's successful undercover assignment earns her an invitation for specialized training in Sacramento.

Officer John Nolan is assigned his first rookie, Officer Celina Juarez, whose unconventional approach to police work poses a unique challenge for him.

Rosalind returns with a vengeance and Bailey's life is left hanging in the balance. With a ticking clock, the LAPD and the FBI join forces.

John and Celina are on the hunt for a fugitive after a car incident goes awry. Lucy helps Tim in his time of need.

Nolan and Celina investigate a cash deposit linked to an old DEA case; Wesley grows increasingly concerned about his deposition and is shocked when he realizes Elijah's attorney is a familiar face.

Nolan and Celina witness a shooting and realize the victim was already dead; Bailey has been feeling off-center since the proposal, leaving Nolan to wonder what he can do to make her feel more comfortable.

Officers John Nolan and Celina Juarez are in a race against time to stop the source of an explosive rampage.

Nolan and the team investigate the death of a suspect in police custody; Grey and his wife go to New York to visit their daughter, only to realize she never made it home from the night before.

Detective Nyla Harper and James find themselves in the middle of a bank robbery which leads the entire team on a citywide manhunt. Meanwhile, Tim and Lucy finally go on their first date, but it does have a few complications.

The team ends up in a gang war while Lucy investigates a domestic abuse case.

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.

In the midst of a heatwave and a citywide blackout, Nolan and Aaron follow increasingly large leads after they discover criminals hiding at the station.

Officer John Nolan and Bailey search for a mystery gunman after a shooting hits a little too close to home; Aaron struggles to live within his means; Wesley suspects that a judge is taking bribes.

With help from the FBI, Lopez puts everything on the line to help Elijah Stone take down a gang leader in exchange for her safety; Nolan and Bailey must deal with the secrets and shady dealings his late mother left behind.

The team must stop a militia from detonating a highly combustible truck in their possession. Meanwhile, Nolan, Thorson, Juarez, and Harper search for three men who may have been exposed to Ebola and detain them for quarantine.

Now that Elijah and Abril have become allies, the team must rely on Monica, Elijah's lawyer, to uncover their plans. Meanwhile, Officers Nolan and Juarez reopen her sister's case and discover a discrepancy that leads them on a new trail.

When Dim goes missing, Officer Chen and Sergeant Bradford, along with the CIA, set out to find him and enlist the help of Juicy.

The team investigates a pattern of kidnappings which leads them to a discovery that hits close to home with one of their own.

Officer Tim Bradford's ex-wife returns and asks the team to help her save someone from her undercover past. Isabel's return also creates additional pressure in Lucy and Tim's relationship as they assist in the search.

Officer Chen goes undercover to infiltrate an illegal firearm operation, and Detective Harper and Officer Nolan work together to solve a mystery involving severed limbs found around the city.

After one of their own is shot, the team suffers a series of close calls and realizes their division may be a target for a group of masked assailants.