Firehouse 51 is forced to share space with Firehouse 17. Kidd and Herrmann fight over Ritter; an arson case tests Kidd and Severide's relationship. Firehouse 51 says goodbye to one of its own.

Mouch sets out to change his legacy and nickname. Ritter pushes Herrmann to see a doctor. Brett searches for the perfect wedding venue.

Brett and Violet decide to take the investigation into their own hands, after witnessing a domestic dispute. Mouch vets Truck 81's new firefighter. Herrmann relies on something new to aid him on the job.

Julia spends a couple days at 51. Boden's stepson, James, returns desperate for Boden to help his mother.

After their defibrillator malfunctions on a call, Brett and Violet search for answers; Herrmann tries to find the perfect home for his new recliner; a secret from Gibson's past comes to light.

Firehouse 51 welcomes back some familiar faces and says goodbye to Brett. Violet scrambles to decorate Brett's wedding venue. A call at the expo center takes a shocking turn.

Violet clashes with her new partner; Severide discovers a hidden stash of money on a call and squares off against the cops; Mouch gets a parking ticket.

A hazmat call at a dialysis center leads to a shocking discovery; Boden clashes with Paramedic Chief Robinson; Carver notices a concerning change in Gibson's behavior.

Severide, Kidd and Van Meter investigate a fire at a recording studio. Kylie helps James keep a secret from Boden. Mouch struggles to maintain boundaries with a paramedicine client.