Chaon Cross

Following the gutsy firefighters, rescue squads and paramedics of Firehouse 51. No field is more dangerous yet so exhilarating, but the personal lives of these men and women provide close competition.

Lt Severide is targeted by an arsonist, Battalion Chief Boden clashes with Gail McLeod the anniversary of Andy's death, Shay has suspicions, and Mari visits Mouch.

Darden's widow publicly blames Severide for her husband's death and Casey makes a decision about his future with Hallie.

Severide tries to prove his suspicions about the arsonist's identity, Casey gets accustomed to his new lifestyle, and Dawson goes on a date with a regular from the bar.

McLeod pushes Boden toward an early retirement and chooses a potential replacement; all make known their disdain for the mole, and Shay enjoys a full social life.

Pete discovers that Chief Boden knows more than he's letting on about the death of his father and Shay decides she's ready to be a single mum.