Francis "Frank" Donovan (Jon Tenney) was the patrol sergeant who presided every day over the morning shift assignments he gave to the uniformed officers.

It was later revealed in the season that Donovan became an undercover informant 15 years earlier for IAB to protect his father, a retired cop living in Florida, from indictment for corruption.

In the pilot episode, a psychotic gunman named Hopkins went on a shooting rampage outside the police station, killing a number of policemen and innocent bystanders.

He was wounded in the shootout and disarmed and handcuffed by Officer Doyle, who later stopped the other cops from beating Hopkins to death and left his barely breathing self in the interview room alone.

Eventually, everyone was exonerated for the suspect's death and Kersey completely got away with it, though her guilt over murdering a critically wounded criminal would haunt her off-and-on for the duration of the series.

Jack Lowery (Titus Welliver) was a tough street cop coping with personal demons which included his selfish and nagging wife, Yvonne, who died early in the season.

Ray MacElwaine (John Finn) was a 50-year-old veteran police officer who transferred to the 74th Precinct late in the series and soon proved himself to everyone that despite his age, he could still "walk the beat" and take down criminals.

Other secondary characters included Kevin Patrick (Mark Kiely), a police officer wounded in the opening shooting spree in the pilot episode, which made him a paraplegic, and his wife Noreen (Star Jasper), both of whom were friends with Jimmy, Terry, and the Doyle family.

At the 74th Precinct in South Brooklyn, a typical day begins with a sudden bloodbath when a deranged gunman named Dawshawn Hopkins opens fire on policemen and random civilians outside the station.

Dawshaun's sister Mavis accuses the white officers of murdering her brother because he was black and teams up with a local civil rights activist and preacher, Basil Matheson, to insist that an investigation be launched.

Kevin Patrick, another officer who was shot in the back during the opening shootout, is comforted by Jimmy Doyle at the hospital when it appears that he might end up paralyzed below the waist.

Elsewhere, Officer Jake Lowery deals with his difficult job and his troubled home life involving his contemptuous, highly strung-out wife Yvonne.

Officer Nona Valentine is also affected by events as well as her former boyfriend, traffic cop Clement Johnson, while rookie newcomer Hector Villaneuva is assisted by Donovan during his first week on the job.