Anthony Ferraris

Dawson and Casey's relationship becomes all the more strained when Dawson breaks protocol during a call-out to a dangerous chemical spill.

Kelly is a law unto himself in his pursuit of Katie's kidnapper, while Dawson's grudge against Rebecca grows when she joins Firehouse 51.

The big wedding day arrives and Firehouse 51 welcomes Casey back to celebrate the joyous occasion; Emma's plans to replace Violet come to a shocking end.

A warehouse blaze puts the fire and rescue squad at risk, Dawson's father overstays his welcome at Dawson and Casey's home, Casey fights for his first responders bill, Mouch makes a serious decision, and Herrmann tries to make a young boy smile.

A series of teen opioid overdoses sees Severide partner with Sean Roman, but he begins to suspect there's more to the story than his old friend is telling him. Casey tries to be there for Brett as she considers her birth mother's offer to meet.

Severide starts off on the wrong foot at his Office of Fire Investigation assignment when, despite orders, he reopens an old case. Herrmann is on a mission to discover what caused an apartment fire and Kidd finds herself burning the candle at both ends.