Rae Gray

Severide finds that he shares a familiar past with Eric Whaley, the Lieutenant who was brought into the firehouse to help out. Dawson lets Shay in on her secret, while Casey deals with family issues.

Labor Days: As Bull prepares for fatherhood, his work at TAC suffers without his top attorney, Benny, who quit in reaction to Bull's romantic re-connection to his ex-wife and Benny's sister, Isabella. In addition, the team faces a difficult time in court as they mount a defence for a young bartender on trial for involuntary manslaughter. (S4, Ep1)

While Alicia and Nick try to find their place, spending time among new crowds, Madison discovers a curious dovetailing between Otto's past and her own.

An oncoming threat disrupts peace, Madison and Troy search for answers, and Alicia must reconcile with her past.

The surgeons are determined to shut down Quovadis after Henry Barnett almost loses his life due to a device malfunction. Meanwhile, Bell, AJ and Conrad work to save the life of Chastain's favourite custodian.

Loyalty wavers at the Ranch and news of incoming danger spreads in the community. Madison struggles to keep everyone together and Nick grapples with a hard truth.