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.

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.

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.

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.

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.

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.

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.

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.

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.