The story of firefighters in Chicago.
Cast: Jesse Spencer, Taylor Kinney, Monica Raymund, Lauren German, Charlie Barnett, Yuri Sardarov, Christian Stolte, Eamonn Walker, Anne Lockhart, David Eigenberg, Joe Minoso, Randy Flagler, Don Kress, William Smillie, Steve Piper, Teri Reeves, Mo Gallini, Nicole Forester, Kathleen Quinlan, Anita Nicole Brown
Severide and Kidd continue to investigate Benny's old arson case. Unexpected news leads Brett to ponder a big decision. All hell breaks loose.
A serial arsonist cold case is reopened when Lt. Severide finds a connection to a recent salon fire. Firehouse 51 celebrates a retirement party.
Severide and Boden search to uncover whether arson was the cause of a fire at a hair salon. Mouch, Herrmann, Otis and Kidd make a startling discovery while tracking down the missing piercing nozzle from Engine 27.
A horrible storm wreaks havoc on Chicago and impacts Firehouse 51 when the power goes off. A little boy mysteriously shows up at the station and everyone works together to uncover who he belongs to. Foster and Kidd argue about Severide.
Severide gets angry at Cruz when he feels his orders were disobeyed in the field. Boden reconnects with an old high school friend during a call to a house fire. Herrmann has issues when one of his favorite knick-knacks from Molly's goes missing.
Tensions run high between Casey and Herrmann after the firehouse responds to an apartment complex fire. After discovering something extremely suspicious during the call, Kidd and Severide do some investigating and get CPD on the case.
Casey struggles after experiencing a narrow miss on a call. Otis wins a unique sporting opportunity in a raffle. Grissom turns to Severide for assistance when the mayor's office sends a task force to Firehouse 51.
A spate of robberies comes to light after a firehouse lockbox key goes missing. Sergeant Hank Voight suspects a firefighter may be involved, and with Boden's support, he recruits Cruz to go undercover to help sniff out any suspicious activity.
Brett, Foster and Kidd take a road trip to Indiana for a getaway and encounter a bus accident involving a boy's hockey team that will leave them scrambling and relying on their instincts to save those hurt in the accident. The rest of Firehouse 51 competes in the annual Chili Cook Off.
Cruz leads the charge in getting the firehouse to gear up for the Polar Plunge. Herrmann has a hard time bouncing back after dealing with a tough call. Foster's personal relationships begin to interfere with her job.
When the firehouse is called to a motorcycle crash, Casey and Severide sense that the details don't add up. A rift develops between Mouch and Otis. Brett, Foster and Kidd work to secretly fix a dent in the ambulance bumper.
Foster faces blowback after pointing out a doctor's oversight. Brett helps Casey look for a new apartment. Kidd prepares Tuesday the Dalmatian for the Fire Safety Dog Competition. A serious accusation is leveled against Severide.
Casey and Naomi fight to escape a raging fire in Casey's apartment; Brett and the team struggle to create an engaging community fire safety presentation; Severide and Kidd's relationship reaches a crossroads.
A car pile-up impacts someone dear to the firehouse family. Brett and Foster encounter a harrowing call while Kidd and Severide find their relationship being tested.
Firehouses 51 is called in to battle a structure fire that places everyone in peril.
Severide struggles to process his father's death; Brett thinks a teenage driver in a car accident is hiding something.
Gorsch takes over Boden's morning meeting at Firehouse 51 and goes out on calls in his place; Brett and Foster respond to a call about a Halloween prank getting deadly serious.
Casey investigates the cause of a trailer park fire; Boden reaches his breaking point; Mouch, Herrmann and Cruz wonder why Molly's isn't living up to expectations.
A series of explosions hit Chicago; Herrmann adjusts to his new duties; Kidd is visited by an old friend.
Boden becomes skeptical of Gorsch's motives; Severide gets involved in a difficult situation following a child's rescue from a car wreck; Foster is tasked with giving Cruz personal advice.
A raging fire consumes a 15-story apartment building complex, trapping victims on the top floors.
Casey struggles with his personal life; the firehouse welcomes a new member; Boden clashes with the new assistant deputy commissioner.