A familiar face returns to Firehouse 51 to serve with Kidd on a special task force. With Tony days away from breaking the CFD's perfect attendance record, Mouch and Capp work to keep him safe. Old memories and grudges resurface when Gallo reunites with a family member.

Herrmann works on becoming a better man after Cindy's cancer journey. Kidd bonds with a homeless victim on a call. Kylie takes her firefighter exams. A harrowing call takes a toll on Brett.