Brett, Foster and Kidd take a road trip to Indiana and encounter an accident involving a boys' hockey team that leaves them scrambling and relying on their instincts to save the injured. The rest of Firehouse 51 competes in the annual chili cook-off.

Tension builds when a group of rabble-rousers attempt to lock down the firehouse. Brett is faced with a monumental decision. Cruz readies himself for a big day. Gallo and Ritter attempt to launch Firehouse 51 into the social media age.

While completing a task assigned by headquarters, Boden makes an unforeseen connection. Gallo is forced to make a surprise rescue to one of their own when the firehouse is called to the site of a construction explosion. Mouch reignites an old feud.

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.

Griffin learns the truth about his father’s death and reveals why he really came to visit Casey. Gallo, Ritter and Violet take steps to expand their microbrewery business.

Cruz forms a bond with a young immigrant boy he meets while fighting an apartment fire. Squad makes plans to prank the newest member of their team.

Herrmann is tasked with fulfilling a man's dying wish. Kidd reflects on her Girls on Fire program after one of her students graduates from the Fire Academy. A heckler harasses Firehouse 51.

An annoying floater takes a romantic interest in Violet. Ritter catches a local politician in a compromising position. Mouch and Severide help Trudy with an arson investigation.

A familiar face returns to Firehouse 51 to serve with Kidd on a special task force. Mouch and Capp work to keep Tony safe, as he's days away from breaking the CFD's perfect attendance record. Old grudges resurface when Gallo reunites with a family member.