Starting over isn't easy, especially for small-town guy John Nolan who, after a life-altering incident, is pursuing his dream of being a police officer. As the force's oldest rookie, he’s met with skepticism from some higher-ups who see him as just a walking midlife crisis. Throw in a workplace romance, a hostage situation, and some tough love from their new training officers, and the latest Los Angeles police rookie class has an uphill battle ahead of them.

Talia forces Nolan to confront his personal moral instincts in order to be a good cop after he encounters a kidnapping victim. Lucy is temporarily placed with a new training officer who tests her patience. Jackson must confront his failures head-on if he wants to be an officer.

After Nolan and Talia lose control of a crime scene, they begin to debate whether people are fundamentally good or bad and what that means for a police officer. Lucy is concerned Tim is enabling his wife’s destructive behavior and not taking care of himself.

The rookies are temporarily paired with new training officers, and Nolan is paired with Lopez. When Nolan and Lopez track down an escaped criminal, they discover a little kindness goes a long way. Jackson is forced to face his fears when he is partnered with Officer Bradford. Chen and Nolan must face a hard truth.

Nolan, the rookies and their training officers get involved in a competition that pits them against each other. Chen notices Bradford is obsessed with winning at all costs.

Nolan and the team must help capture a cop and his former mentor from the academy after he becomes a fugitive following an assault. Bradford needs Chen to learn to predict the moves of criminals in order to capture them.

Grey informs Nolan and Bishop that they are going to have a movie director as a ride-along during their patrol after a fun afternoon granting the wish of a Make-a-Wish kid as an honorary police officer. Bradford is tested once again after he learns that his wife has been arrested for drug possession.

Nolan and Bishop respond to a silent alarm call at a local convenience store where two men are attempting to rob the place. Bishop helps coordinate a drug bust that hits a little too close to home for Bradford.

Officer Bradford’s wife, Isabel, is found shot but alive and he vows to track down the man responsible. Meanwhile, Officer Nolan must protect his home and the truth after a home invasion attack.

On Captain Andersen’s orders, Officer Nolan and Sergeant Grey are paired up for the day on patrol. Additionally, Nolan’s son and Grey’s daughter visit their dads on the job and see them in action. Meanwhile, Officer Chen is paired up with Captain Andersen, and Officer Bradford tells Chen to protect her at all costs.

An unscheduled visit by the vice president of the United States puts the station on high alert. The secret service tasks Officer Nolan and Officer Bishop with checking out a possible threat to the vice president while the rest of the team try to keep the streets clear and safe for his visit.

The most dangerous day of the year – Valentine’s Day – has the team on high alert, and Officer Nolan invites everyone over for a party now that he is single.

The rookies become the prime suspects after it is discovered a large sum of money used in a drug bust has gone missing.

The rookies are really put to the test when their training officers accompany them out of uniform for Plain Clothes Day, which forces them to make all the decisions while on patrol. Meanwhile, Officer Nolan tries to prove he has been progressing faster than the other rookies to justify his desire of becoming a detective within five years.

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.

Officer Nolan gets a lesson in respect after his arrest of a gang member leads to a free-for-all on his life. Meanwhile, Officer Chen and Officer Bradford pull over Mario Lopez, who thinks he can talk his way out of a traffic violation.

A massive earthquake rocks the city and throws everyone’s patrols and its citizens into chaos. Meanwhile, agent Russo recommends Officer Nolan for a protective detail of Brad Hayes, a man whose dealings have put a target on his head.

When one of their colleagues is arrested by Internal Affairs for lying on the witness stand, it leads to the release of three felons whose cases he worked on and the team being asked to check in on them now that they are free. Meanwhile, Officer Nolan finds out he is being sued by a man who claims he used excessive force which led to an injury.

Sergeant Gray informs the rookies that they must track down a specific set of crimes in a 48-hour period in order to qualify for their final exam. Meanwhile, Officer Nolan and Officer Bishop answer a silent alarm call at will.i.am’s house.

As the rookies prepare for a big exam to see who moves on to the next stage of training, Officer Nolan and Officer Bishop are called to the scene of a murder and learn that the victim may be tied to a potential terrorist attack on the city of Los Angeles.

Danger is ever-present as the officers of the Mid-Wilshire precinct grapple with the aftermath of a plotted attack on the city of Los Angeles, leaving Officer Bradford fighting for his life.

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.

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.

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.

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. Meanwhile, Officer Bradford and Office West are assigned a community policing project helping out the Watts Rams as volunteer coaches at their fall clinic, along with Rams players Eric Weddle and Robert Woods.

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’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 and team are charged with escorting a notorious female serial killer to the graves of her previously unrecovered victims. However, when they arrive, they unearth even more than they expected. Meanwhile, Officer Chen meets a seemingly perfect man who sparks her interest, and Officer Lopez worries about Wesley as his PTSD continues to increase.

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.

Nolan takes his son’s fiancé, Abigail, on a ride-along after she shows interest in becoming a police officer. Meanwhile, Jackson’s relationship is becoming complicated at work.

Nolan is given some life-changing news and invites Grace over for a homecooked meal in his newly remodeled kitchen. Meanwhile, each unit is tasked with following up on dormant cases in the hopes they can uncover new leads.

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 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 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. Meanwhile, 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. Meanwhile, Lucy’s fear of dating following her abduction and her intrusion into Jackson’s relationship is beginning to threaten their friendship.

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.

Their rookie year is coming to an end and officers Nolan, Chen and West are about to be squeezed harder than ever before as their training officers evaluate whether they are truly ready for the job. Meanwhile, after one of their rookie classmates is involved in a shooting, the team uncovers some unsettling evidence .

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