When a call comes in from the Cook County jail, the squad steps into a volatile predicament and are tasked with trying to defuse an escalating situation. Shay remains hopeful about her baby dreams and Hermann's wife Cindy goes into labor with their fifth child. Meanwhile, Mills and Dawson face key decisions in their personal lives.

An arsonist targets Lt. Severide. Meanwhile, Station 51 is under scrutiny by Gail McLeod, a financial consultant for the city who is deciding if any firehouses should be closed. Mouch receives a visit from his Japanese girlfriend, Lt. Casey "celebrates the one-year anniversary of Andy's death, and Shay suspects Severide's paternity.