Severide puts his job on the line to help out one of their own. Kidd navigates Natalie’s complicated relationship with her sister. Herrmann prepares to take the Chief test.

Kidd strengthens her bond with Natalie during a road trip. Severide investigates a car fire and uncovers surprising evidence. Violet receives a career opportunity.

With the crew stretched thin, a performance efficiency expert evaluates Firehouse 51. Kidd and Severide bond with the mother of the baby they hope to adopt.

Severide investigates an old house fire from 10 years back in which Kidd had responded. Carver and Violet search for a mystery medic who abandoned a victim. Novak looks for a roommate.

Deputy Commissioner Boden (Eamonn Walker) returns to Firehouse 51 to investigate a disastrous firefight and the surrounding mystery that left one of their own in peril.

Kidd connects with a troubled teen interested in Girls on Fire. Cruz, Capp and Tony wait to try out Squad’s new saw. Violet and Novak are stumped by a bodybuilder who passed out at the gym.