Mannion issues a mandate to get illegal guns off the streets and uncovers the surprising motive behind the murder of a well-connected young man.

As Mannion vows to clean up the most crime-ridden block in the city, community tensions rise when Temple is accused of intentionally pushing a police suspect into oncoming traffic.

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.

The city is terrorized by a criminal who stalks elderly people, empties their bank accounts and then kills them; the Mayor comes clean about his sordid past; Ella is asked out on a date, but she's not sure if she should accept.

Mannion becomes personally involved in a case after a woman asks him to find her husband; McGregor threatens a former I.R.A. gunman who is in town for peace talks.