Firehouse 51 is forced to share its 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.
Severide goes for an unexpected ride on Truck 81. Ritter's worlds collide when his secret cop boyfriend helps 51 track down Severide and the missing rig.
Severide steps in as ranking officer at 51. Kidd fights to save her Girls on Fire program.
Mouch sets out to change his legacy and nickname. Ritter pushes Herrmann to see a doctor. Brett searches for the perfect wedding venue.
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.