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 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.

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.

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

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 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.