Ella is fearful of what will happen to Ricky when he testifies against his father, who's on trial for murdering the boy's mother; Temple tries to convince the victim of a serial rapist to testify; Nick discovers some explosive evidence against the mayor.

Mannion vows to better protect cab drivers after a cabbie fatally shoots a passenger he thought was trying to rob him. Also, a new U.S. Attorney stirs up controversy, and McGregor gets jealous when Nancy receives flowers from an unknown person.

Mannion decides to declare war against street gangs after a drive by shooting kills an innocent pedestrian. Two Latino gangs (the ""Colombian Guardian Crew"" - C.G.C. - and ""Los Muertos"") - one Cuban and one Salvadorian - are in war with each other over territory limits and Mannion sends his best men to catch the main leader accused of killing the pedestrian: Carlos ""El Gato"" Cesar, one of the most dangerous gang members in the city. Meanwhile, Mannion has suspicions that the same man that reported a criminal fire is the one who started it; and Nick has to face his fears after being badly beaten up by a robber.

Detective Travis Haywood is shot while performing an undercover operation by an off-duty cop. Mannion has to handle the manipulative press that keeps referring to the incident as the third time a black cop has been shot by a white cop. Detective Heywood dies and the issue of prejudice gets stronger as the black cops demand the shooter to be severely punished.

Two ex-cops who worked as bank securities are shot to death and Mannion suspects that the Russian mob is behind it. The FBI wants the case, but Mannion won't let go and decides to solve it by himself. He contacts Monya, a Russian gangster from NY with whom he has a history and Monya gives him a name to go after. The FBI wants to take over the investigation and Mannion refuses to help them given the issues he has with the bureau back from when they let his old partner die. After a few insults that cross the line of internal rivalship, compromising evidence from Jack's personal account appear to incriminate him, possibly planted by the federals.

Meanwhile, Temple's marriage is approaching and he couldn't be happier. But his plans are suddenly interrupted when he pays his fiancée a visit at the hospital. Two men had just arrived from a neighbor fight over a fence, and one of the victim's brother goes insane and tries to shoot the other man. But McGregor throws himself to protect the man a

When two children are shot by a 7-year-old boy, Mannion makes it his mission to find exactly how the boy got his hands on a gun.

When Mannion questions the 7-year-old, he learns that the youngster took the gun from his 15-year-old brother who reveals that he got the gun from a ""guy on the street"" near his school. With the help of Temple and Debreno, Mannion sets up a sting and discovers that the weapon was actually a gun that the police had confiscated in a ""buy-back"" program. Now, with the Public Safety Commission breathing down Mannion's neck, he must track down the culprits before any more guns hit the street or any more children get hurt.