Dawson saves a young boy from an apartment fire. Kidd’s idea for Molly’s doesn’t go as hoped. Severide hits a wall while advocating for new fire masks. Cruz and Brett utilize a secret weapon to get Otis to see Dr. Halstead take a blood test.

Firehouse 51 unites to help a young boy in tragic circumstances. A high-powered political consultant helps Casey navigate a potential scandal. Cruz makes a mistake that nearly costs him his life.

Casey steps up to help a teenager being bullied by a gang; Severide bonds with a detective’s son after her life is threatened; and Kidd and Herrmann go head-to-head in a test of bar knowledge.

Sylvie witnesses a murder and is threatened by the shooter not to go to the police. Firehouse 51 jumps into action when a fire breaks out at a restaurant and traps several people inside a vault. Mouch starts to get cold feet.

Severide and Cruz find a child’s remains inside a chimney while investigating a possible carbon monoxide leak inside a home. In other events, Casey braces for the worst in his run for alderman while Alderman Becks continues to bad mouth him to the press.

Casey reconsiders his run for alderman after he’s targeted by a propaganda campaign. The squad responds when a man is trapped inside of a burning car. Trudy’s nerdy brother plans Mouch’s bachelor party. Jimmy and Brett investigate a kidnapping on their own.

The team responds to a suspicious call from a neighboring firehouse; and welcomes a new firefighter, though her addition has repercussions. Casey moves forward in his run for alderman.

Severide confronts Chili about her erratic behavior. Members of the firehouse rally around Casey, who they think would make a great candidate for alderman. Jimmy squares off against Antonio in the first annual “Battle of the Badges” boxing match.

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.

Freddie’s father begs Herrmann to forgive his son’s assault. Casey discovers that a makeshift shelter housing people displaced by the tornado may close. Casey attends a fund-raiser at the request of an alderman. Dawson and Brett experience repercussions after telling Boden about Chili’s erratic behavior.

A tornado threatens Chicago. Chili makes a major mistake, which causes Brett to report her to Boden. Otis asks Dawson to help him solve his women troubles. Severide assists a Department of Homeland Security agent.

Herrmann fights for his life after being stabbed; Cruz hits the streets to find Freddie. Mouch proposes to Trudy.

The crossover continues on Chicago Med S01E05 Malignant (II) and Chicago P.D. S03E10 Now I’m God (III).

Patterson fills in for Boden, who’s trying to clear his name. Severide learns where Serena may be hiding. Herrmann and Otis give Freddie a job that keeps him close by. Jimmy and Chili draw more attention then either bargained for.

Boden believes Maddox is behind Serena’s accusations. Severide reaches out to Jamie, who’s Maddox’s lawyer, in an attempt to help. Patterson questions whether Boden can remain chief. Brett and Chili suspect that a man passed out in a garden is connected to a previous call. Otis has problems with his social calendar.

Boden suspects his neighbor is setting him up; Severide, who’s still on probation, receives a surprise visit from his father and also learns something about Patterson that could be a game changer. Romance blossoms at a fire department gala.

Boden’s new neighbor asks him for a favor that could have serious repercussions. Severide is upset when he’s treated like a candidate by Patterson. Cruz is visited by a gangbanger who knows his brother. The team responds to a call that involves an 18-wheeler; and is thanked with tickets to see Rush.

Boden offers to host a wedding at the firehouse after a fire destroys the original location, but it doesn’t sit well with Chief Riddle, who also butts heads with Dawson over her ability to perform. Severide fights for his old position. Capt. Patterson finds himself torn between leadership and his colleagues.

The squad members come together to support one of their own. Herrmann tries to figure out how to reopen Molly’s after it gets shut down. Severide digs deep into the arson investigation.

Evidence that seems to exonerate Boden may not be enough. Brett and Chili find themselves in a precarious situation. The team responds to a stuck elevator in a hotel. Jimmy Borrelli’s older brother wants him transferred to a different house.

Boden’s job is on the line pending an internal investigation. Severide adjusts to Patterson, his new commanding officer. Dawson shakes things up at the work. Casey searches for important evidence in his investigation of Nesbitt. Herrmann tries to keep the peace with Molly’s new neighbors.

Casey is placed in a dangerous situation while working undercover to bring down a trafficking ring being run out of Nesbitt’s club. The squad’s high turnover rate results in an unwelcome surprise for Severide. Dawson recognizes that her life is about to change. A new candidate makes an unusual first impression. Residents band together to protest a drug den in their neighborhood.

Lt. Casey puts his life on the line and digs deeper into the shady dealings of Jack Nesbitt. Chief Boden must figure out how to create unity in a divided house, while Severide comes to question his own judgment. A dangerous warehouse blaze quickly gets out of control and threatens members of firehouse 51.

At Sgt. Voight’s urging, a determined Lt. Casey agrees to go undercover in an effort to provide proof of Jack Nesbitt’s shady dealings. Meanwhile, Otis and Severide continue to disagree about the integrity of Scott Rice, causing tensions to flare between members of truck and squad. Meanwhile, Herrmann helps out a fellow member of the firehouse.

An apartment fire connected to a case of rape and attempted murder resembles an unsolved case in New York, so Sgt. Benson of Special Victims Unit comes to Chicago to help Intelligence with the investigation.

(The Number of Rats (2) aired on Chicago P.D., S2E20. Daydream Believer (3) aired on Law & Order: Special Victims Unit, S16E20.)

The teams will track a Ted Bundy-esque killer who hunted in New York and in Chicago. This crossover event will go back and forth between the two cities, integrating the story a lot more between the different teams in Chicago and New York.

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.

Herrmann tries to rescue a toddler from a structure fire. Mills discovers unexpected news.

Severide lobbies Chief Boden for a favor for Scott Rice, an old friend needing a second chance with the CFD, but Casey and Otis have their doubts. Elsewhere, Mills works to regain his active squad status while Brett and Dawson decide they need a big night out.

The interim chief makes a tactical error during an apartment fire, stirring up tensions and putting careers in jeopardy. Meanwhile, Mouch discovers that his donation to a fertility clinic has resulted in a child, and Dawson goes out on a double date with Brett and Cruz.

A temporary chief fills in for Boden, who is forced to take some time off for personal reasons.

An ice storm hits, forcing a citywide lockdown. Mills and Brett are left stranded in the elements while searching for a teen, and the firehouse members babysit a newborn. Elsewhere, Severide receives a job offer, and Chief Boden clashes with his father over his treatment.

In part one of the crossover with Chicago P.D.: Additional clues about Shay’s death emerge. Meanwhile, Severide faces an old foe; Shay’s sister arrives, inspiring the firehouse members to reflect on her life; Otis’ grandmother relocates; and Boden sets out to help his dying father.

(A Little Devil Complex (2) aired on Chicago P.D., S2E13.)

Severide and Dawson unearth shocking evidence about the fire that killed Shay. Elsewhere, the firehouse bonds over a serious car accident, and Chief Boden’s father visits, only to give unsolicited parenting advice.

Two firehouse members are abducted, triggering a desperate search by the Chicago P.D. Elsewhere, Casey and Dawson struggle to balance their personal and professional lives, and Chief Boden deals with news that his newborn has potential complications.

A house fire sees the team attempting to save the lives of a couple trapped inside. Chief Boden prepares to start his new family. The combination of life at work and home sees Casey and Dawson drifting apart.

Dawson and Casey’s relationship is tested as the team responds to a truck leaking hydrochloric acid in a busy intersection. Severide learns about Brittany’s past. Mouch has dating troubles.

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

In part one of the crossover with Law & Order: During a house fire, Firehouse 51 rescues the owner from the cellar clutching a suspicious box, leading Lt. Severide to bring in Sergeant Voight and Detective Lindsey for further investigation.

(Chicago Crossover (2) aired on Law & Order: Special Victims Unit, S16E07. They’ll Have to Go Through Me (3) aired on Chicago P.D., S2E07.)

Casey faces his corrupt brother-in-law and Brett goes above and beyond to help a mother in need. Meanwhile, Mills get an education on unlicensed private investigation and Dawson begins training with Herrmann.

Casey deals with the aftereffects of his sister’s divorce announcement. Dawson and Mills get used to their new roles at Station 51. Brett ponders whether to leave Chicago. The Molly’s crew works to get the food truck started.