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.
Boden pushes his team to pull it together in the aftermath of the explosion, Casey works to track down a missing Severide, Newhouse brings news about one of Mills' relatives and Herrmann and Otis come up with new goals.
Darden's widow publicly blames Severide for her husband's death and Casey makes a decision about his future with Hallie.
Severide is on edge after the arson attack, fearing what might be in store next. Shay and Dawson, meanwhile, plan to party away their problems.
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.