The Rookie - Season 4 (2021)

Officer Nolan and Officer Chen search for a missing person who may have international ties that puts everyone's lives in danger; Harper continues the search for a serial arsonist; Wesley must overcome an impossible task.

When a new designer drug hits LA streets, it turns users into "zombies," and Officer Nolan and the team have a Halloween they won't soon forget. Back at home, Lucy questions whether her apartment building might be haunted.

Officer Nolan and team are on a hunt to retrieve a buried stash of gold before any treasure seekers get hurt. Meanwhile, Bradford is tasked with encouraging the oldest cop at the station to retire and invites him to ride with him.

In the aftermath of Fred's house explosion, Officer Nolan and Bailey discover there's more to Fred's death than meets the eye. Meanwhile, Officer Chen and Officer Bradford demand a treasure hunt rematch and enlist Officer Grey to help set the terms to a new bet, all while they arrest a series of wealthy female criminals. Elsewhere, Wesley struggles to keep it together under the pressure of his debt to Elijah.

The squad encounters a sovereign citizen and deals with a domestic terrorist plot. Angela and Wesley argue about their predicament.

Wesley finally manages to break free of his dirty contract. Nolan deals with an increasingly serious relationship and underhanded election techniques. Bradford learns some unpleasant things about his parents.

Now that John Nolan knows about Bailey's past, he must decide if they still have a future; when a plane crashes in the middle of the city, the team races to find out why.

The team must rely on a criminal for his expertise to take down a bigger threat. Officers Chen and Bradford investigate a murder of a homeless teenager.

The team responds to the report of a severed hand that has washed up on the beach. Tim attempts to prove his isn't a control freak to Lucy and invites her on a double date.

John Nolan and Lucy Chen must fulfill three quests if they want to get a stolen police helicopter back safely from a teenage thief; Nyla Harper and Aaron Thorson must guard a convicted cop killer in the hospital following a prison riot.

Nolan and Harper help Skip Tracer Randy complete his first bounty. Officer Chen and Sergeant Bradford hunt for a perpetrator on a citywide crime spree.

Harper puts Thorsen through "Plain Clothes Day," but the exercise is interrupted by an unexpected visitor. Meanwhile, two witnesses for an upcoming grand jury case are murdered, and Sgt. Grey might be next on the list.

Thorsen's documentary crew does another update with the squad.

Officer John Nolan and the team feel they must negotiate with a distraught man who is holding a hospital hostage to ensure his wife receives a lifesaving surgery.

The robbery of a freight train filled with valuable auction items turns deadly, and the team is called to investigate. Officer Chen has doubts about being Sergeant Bradford's aide and is upset when he doesn't give her the recognition she deserves. Officer Harper takes matters into her own hands and makes a life-changing decision about her personal life.

Officer Nolan and the LA division of the FBI enlist the help of FBI trainee Simone Clark when one of her former students is suspected of terrorism following an explosion at a local power station.

The team, alongside the LA division of the FBI, is in a race to stop truck bombs. The join task force is suspicious of the CIA's involvement.

Sgt. Grey supports Officer's Nolan to become a training officer and rides with him to help him prepare for the exam. Tim and Lucy decide on their plans for Mother's day and a romantic vacation.

Officer Nolan is forced to spend a week in solitary confinement in a quiet border town with a young local officer who is in need of some training; Sgt. Bradford and Officer Chen go under cover together in a possible drug trafficking case.