Casey tries to deal with his unsettled personal life and the firehouse welcomes a new member. Boden clashes with new Assistant Deputy Commissioner Jerry Gorsch.
In the first part of a three-show, one-night crossover event, Firehouse 51 is faced with a daunting challenge when an out-of-control blaze consumes a 15-story apartment complex, trapping victims on the top floors. Complicating the rapidly escalating situation, members soon discover that someone close to home may be one of the trapped victims.
Chief Boden becomes increasingly skeptical of Assistant Deputy Commissioner Gorsch's motives, while Severide gets wrapped up in a difficult situation following the rescue of a child from a car wreck. Trying to fit in with the rest of the firehouse, Foster is tasked with doling out some personal advice to Cruz.
Firehouse 51 is on high alert when a series of explosions rock the city. Herrmann adjusts to his new duties and Kidd gets a visit from an old friend.
Working alongside a journalist, Casey does some digging into the cause of a trailer park fire. Boden hits his breaking point while Mouch, Herrmann and Cruz work to figure out why Molly's isn't performing up to expectations.
Halloween is in full effect for Foster and Brett, who are summoned to a home where a prank has quickly turned serious. Gorsch continues his reign of terror on Firehouse 51.
Severide faces some major adversity and Kidd is on a mission to help in any way she can. Following a car accident rescue involving a teenage girl and her young sister, a suspicious Brett has an unsettling feeling there is more to the story than what appears on the surface.
Firehouse 51 is called in to battle a dangerous structure fire that places everyone in peril. Severide makes a big personal realization. Casey lends another helping hand to Naomi, the investigative reporter.
Stakes are high when a massive car pile-up on the freeway impacts someone dear to the firehouse family. Brett and Foster encounter a harrowing call while Kidd and Severide find their relationship being tested.
A dangerous situation leaves Casey and Naomi in peril. Foster and Brett are in charge of planning a field trip visit to the station while Severide and Kidd go through tough times.
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.
When the firehouse is called to a motorcycle crash, Casey and Severide sense that the details don't add up and work to determine exactly what transpired. A rift develops between Mouch and Otis. Brett, Foster and Kidd work to secretly fix a dent in the ambulance bumper they believe they unknowingly caused.
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.
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.
A spate of robberies comes to light after a firehouse lockbox key goes missing. CPD's Voight has suspicions that a firefighter may be involved, and with Boden's support he recruits Cruz to go undercover and help sniff out any suspicious activity.
During an emergency call, an unsuspecting Lt. Casey suddenly finds his life in peril. Grissom warns the firehouse that they will need to gear up for a performance evaluation. Otis discovers he won a raffle prize at a recent fundraiser and Brett is met with challenges in her personal life.