The firehouse reacts to some exciting news, a mysterious stranger arrives, and a shocking call takes Severide's breath away.
A fire breaks out at a pet food factory, and Casey and Severide help the owner, Pete, get to the bottom of it; the annual garage sale takes place at 51 and everyone is on edge.
Severide and Casey try to find the best fit for Kidd; Ritter, Gallo and Violet help plan an event for Mouch.
An imperilled, mysterious caller relies on Kidd to help save her and her brother; the firehouse helps Cruz get ready for fatherhood.
When the team consults for the NYPD on the defence of a police officer accused of excessive force in the shooting of an unarmed man, the social politics surrounding the case create tension within their own ranks.