A dangerous warehouse fire puts truck and squad at risk. Tensions are high for Dawson and Casey when Dawson's father overstays his welcome at their home. Meanwhile, Casey continues to fight for his first responders bill, Mouch makes a serious decision regarding his future and Herrmann goes to tremendous lengths to make a young boy smile.

Truck and Squad clash after a tense call rescuing a doomsday prepper. Herrmann struggles with Cindy's diagnosis. Violet gives Brett and Gallo dating advice.

Lt. Casey and Dawson volunteer to help at a charity run at Chicago Medical when a massive explosion sends Chicago into chaos. With one of their own missing in the blast, the firehouse is tested like never before. The crossover continues on Chicago P.D. S01E12 8:30 PM (II)

A fire at a boarding school leaves Lt. Severide shaken and wondering if he could have done more. Meanwhile, with the firehouse in full support of Dawson as she retakes the fireman’s exam, Lt. Casey attempts some political maneuverings on her behalf. Elsewhere, Mills looks for answers about his father’s mysterious past and Chief Boden’s grand plans take a detour.

The mattress factory fire spirals out of control. Truck and squad lay it on the line in hopes of getting the trapped victims out alive.

Chicago's first responders unite in the wake of a catastrophic gas explosion and fire that threaten a city government building. Herrmann reluctantly shadows Pascal while Violet, Novak and Dr. Frost take charge of triage efforts on site. The crossover continues on Chicago Med S10E11 In the Trenches (II) and Chicago P.D. S12E11 In the Trenches (III).

When a tanker collides into a commuter train that subsequently crashes into a warehouse, the firehouse is called to the horrific scene that tests everyone to the limits as life and death hangs in the balance. With the ultimatum in place for him or the firehouse, Boden is tasked with making life-changing decisions regarding his future. Severide learns more about Katie, the young woman he saw with his father. Meanwhile, Shay and Dawson are still at odds and Casey’s responsibility of being a surrogate father takes a sharp turn.

The Chicago fire team works seamlessly with Chicago Med personnel to help aid victims of a deadly gas leak, but things quickly take a turn for the worse when the hospital is suddenly forced into quarantine.

The team responds to a mass shooting; Casey investigates the missing money from the fund-raiser. Jimmy agrees to represent the firehouse in a boxing match against the Chicago PD's 21st District. Chili's behavior continues to be an issue for Brett.

Casey and Dawson find themselves in the midst a potential political mess. Stella has to make a big decision about her ex-beau. The squad responds to an auto accident. Severide befriends a socialite. Brett and Mouch set aside their writing differences for the greater good.

Severide agrees to a bone marrow donation but a work accident throws everything into flux. Casey and Dawson try to find harmony at home. Meanwhile, Otis and Mouch decide to film a PSA encouraging people to join the Chicago Fire Department but hit a creative wall in the process.

Tragedy strikes when a rescue attempt at a tenement building proves unsuccessful, leaving the men and women of firehouse 51 affected by the loss of the victim. Severide's decision to put Mills on the fast track to move from Truck to Squad doesn't sit well with some of the others and tension mounts between Severide and Casey over Heather Darden. Shay and Dawson are forced to deal with a junkie's crazy behavior while on a call and Shay considers a different way to have a family. Meanwhile, the team draws the ire of local drug dealers who threaten the peace and safety of the neighborhood and firehouse.

All seems lost with firehouse 51 on the verge of closing its’ doors, thanks in no small part to Gail McLeod, but Chief Boden and the rest of the house refuse to allow themselves to sit by and let it happen. An emergency call to an apartment structure fire tests everyone’s limits and puts the squad in harm’s way. Meanwhile, Dawson receives some life-changing news and union president Greg Sullivan makes headlines, which has an immediate impact on Mouch.

A rare but deadly bacteria takes its toll on numerous victims around the city, leaving Chicago’s finest first responders to work together alongside the CDC to resolve the dangerous situation. Following a fire at a local university that ties into the outbreak, Severide has suspicions that something bigger is happening. The crossover continues on Chicago Med S05E04 Infection, Part II (II) and Chicago P.D. S07S04 Infection, Part III (III).

Mouch builds a classic firetruck model for the Deputy District Chief but needs some assistance from Gallo and Ritter. Brett and Violet encounter multiple victims with a strange set of symptoms. Cindy's chemotherapy results loom over the Herrmann family.

Brett waits for life-changing news. Herrmann encounters a psychic with a grave warning on a call. Kidd finds a new lead on the Homeland Security case.

A frustrated Severide, turns to an unlikely ally to resolve his current dilemma. Casey begins to find satisfaction in his personal life, while Mills and Dawson face personal challenges. Meanwhile, the squad is called to the scene of a harrowing apartment building collapse.

When a drunk driver knocks down a transformer, the entire neighborhood is left without power on a frigid Chicago night and members of Firehouse 51 step up to lend their much needed help. While many from the community ride out the night at the station, in the midst of such close quarters, romances speed up and tempers flare. Meanwhile, Casey continues to lie to both himself and Dawson about his condition and the stakeholders in Molly's bicker about the bar's direction.

Tensions run high when trucks from two firehouses collide and fingers are pointed towards Cruz for his driving.

The members of the firehouse spring into action when a helicopter explodes over a populated area.

Lt. Casey finds himself in a bad spot when a forklift accidentally pierces a tank storing acid. Casey is forced to use extreme measures to help a father and daughter in peril. Dawson and Brett respond to an elderly woman who has a difficult senior advocate. Mouch and Brett continue with their secret project. Otis shares some exciting news as he prepares himself for an unusual expedition.

While responding to a call in the field, Dawson accidentally hits a pedestrian who stepped in front of the ambulance, and is left to deal with the repercussions. Lt. Casey and Lt. Severide disagree and continue to investigate an arson case while Chief Boden is left to decide whether to attend an important function in New York. Elsewhere, in hopes of preparing him for a possible promotion, Lt. Casey puts Herrmann at the helm for a shift so he can discover firsthand what his superiors deal with.

Severide and Kidd continue to investigate Benny’s old arson case, unexpected news leads Brett to ponder a big decision and all hell breaks loose.

The surprising arrival of a new fire truck brings both joy and chaos to members of Firehouse 51. Boden and Severide are asked to make peace with an old foe for the greater good. Brett receives family news while Foster plans a party with friends.

The firehouse reacts to some exciting news, a mysterious stranger arrives and a shocking call takes Severide's breath away.