A death in custody is reported, but the prison warden says that no one's died. Da Vinci investigates. Shannon and Leary lead the homicide team in the search for a young boy who disappears after his mother is beaten to death.

Da Vinci investigates a body in the sewer. Meanwhile, Brian accompanies Rose on a homicide case, and Kosmo is troubled by a witness from the past, at the same time that Shannon, while moonlighting as a hotel security guard, discovers some dirt.

Da Vinci gathers his political allies hoping to emerge as a front-runner for mayor. Meanwhile, Leary races to arrest Will's murderer before the DEA can slip him across the border, and a body in a burned-out car and an arson fire at Kosmo's house may be ominously connected.