Everyone in the 55th Precinct faces their worst fears when terrorists are discovered to possibly be building a dirty bomb. Carlos and Levine face trouble in their relationship. Captain Finney decides to end his life, rather than surrender himself for the murder of Ty Davis Sr. Brendan and Davis try to cover it up.

Finney gets a frantic phone call from Ben, a child he had helped in a previous case, which said that Ben's father was hurting Ben's mother and coming after Ben. Ben's father takes him to an abandoned warehouse, where the police soon follow.