( Eric Winter ): A tough and traditional Training Officer (TO) known for his "sink or swim" mentoring style.

Follows Nolan as a "P2" (Police Officer 2), no longer a rookie, dealing with more complex cases and international threats. Nathan Fillion

(Mekia Cox): A former undercover detective who joins as a TO in Season 2. Summary of the First 4 Seasons

The series features a strong ensemble cast, with each episode typically following three sets of officers on patrol:

( Nathan Fillion ): The protagonist determined to make his second shot at life count.

Explores social justice issues, internal department ethics, and the rookies nearing the end of their probationary period.

( Richard T. Jones ): The Sergeant who initially opposes Nolan's presence but eventually respects his dedication.

Focuses on the rookies' second half of training and the arrival of Nyla Harper as Nolan’s new TO.