How many crossover events has One Chicago aired so far? A detailed overview of every episode

NBC's prime-time lineup includes One Chicago. The franchise, which includes the hit shows Chicago Fire, Chicago Med, and Chicago P.D., is famous for its interconnected stories, which let characters from different fields work together often. On January 29, 2025, the last big One Chicago crossover event happened.

The One Chicago franchise has aired a total of 14 major crossover events. Chicago Fire is about the brave firefighters at Firehouse 51, Chicago P.D. is about the tough cops in the Intelligence Unit who fight dangerous crimes, and Chicago Med is about the dramatic life-and-death situations at Gaffney Medical Centre. The storylines created moments when Severide, Voight, and Will Halstead work together to solve problems that affect the whole city.

One Chicago: Each Crossover Explored as per Episodes

The One Chicago franchise had a total of 14 crossover events, including other Dick Wolf productions like Law & Order: SVU and the short-lived Chicago Justice.

1. Chicago Fire Season 8, Episode 4, Infection: Part I, Chicago Med Season 5, Episode 4, Infection: Part II & Chicago P.D. Season 7, Episode 4, Infection: Part III

This eighth-season crossover came with a deadly virus. The fire department handled multiple collapses and panic. It sought medical and police help after spotting an epidemic. After infected patients overran Gaffney Medical Center, crisis moved there. Dr. Will Halstead and the medical team raced to identify the pathogen and find a cure despite a citywide outbreak and infection risk. The police sought the pathogen's perpetrator. Final installment: Voight's team fought time to stop the public health crisis.

2. Chicago Fire Season 7, Episode 2, Going to War, Chicago Med Season 4, Episode 2, When to Let Go & Chicago P.D. Season 6, Episode 2, Endings

The Halstead brothers' family issues dominated this event. The fire department met the Halstead patriarch during a major emergency. Dr. Will Halstead, Jay's brother, had medical and family issues. The hospital backdrop forced difficult personal decisions and work-family balance. The police oversaw the conflict, which now involved Jay Halstead. Voight's team had to solve the family mystery in the episode.

3. Chicago Fire Season 4, Episode 10, Chicago Med Season 1, Episode 5 & Chicago P.D. Season 3, Episode 10

The event was initiated by Christopher Herrmann of Firehouse 51. The drama is triggered by emotional pain and emergency response. The story is about the aftermath of the attack and his subsequent survival efforts. The hospital Med team and Dr. Rhodes fought to save a critically injured Herrmann. His colleagues' medical procedures and emotional vigil showed the importance of One Chicago first responders' interconnectedness.

4. Chicago Fire Season 5, Episode 15, Deathtrap, Chicago P.D. Season 4, Episode 16, Emotional Proximity & Chicago Justice Season 1, Episode 1, Fake

This began with a massive, intentional warehouse fire that killed dozens. Firehouse 51 immediately recognized the suspicious fire and massive tragedy. The Intelligence Unit investigated the suspicious fire as mass murder. The firestarter was sought by Voight's team. The spinoff about the suspect's trial ended the crossover. The complex trial and conviction of the perpetrator was the city's final justice.

5. Chicago Fire Season 7, Episode 15, What I Saw & Chicago P.D. Season 6, Episode 15, Good Men 

Intelligence Unit's Hank Voight recruited Fire's Joe Cruz to go undercover. Cruz's sacrifice and the goal of stopping the crime tied the two departments together. The P.D. episode focused on the undercover operation, a typical police procedural involving surveillance and infiltration to catch criminals.

6. Chicago Fire Season 8, Episode 15 Off The Grid &Chicago P.D. Season 7, Episode 15, Burden of Truth

A key character went missing, requiring both departments' resources. The Fire half focused on the initial shock and the firefighters' desperately searching for their colleague using city knowledge. The P.D. Intelligence Unit used lead tracing and intense interrogations to find the missing person and resolve the crisis.

7. Chicago Fire Season 5, Episode 9, Some Make It, Some Don't & Chicago P.D. Season 4, Episode 9 Don't Bury This Case

Two events occurred when a major fire and a criminal investigation. The Fire episode showed the dangerous response to the fire, which revealed foul play. The P.D. episode continued with the Intelligence Unit investigating an arson attack. 

8. Chicago P.D. Season 5, Episode 16, Profiles & Chicago Fire Season 6, Episode 13 Hiding Not Seeking 

This crossover began with the police show, oddly. Firehouse 51-related crime found by Intelligence Unit. Fire addressed the crime's internal threat to firefighters, while P.D. focused on the initial investigation. This reverse order revealed how police work can cause fire department crises in the crossover structure.

9. Chicago Fire Season 3, Episode 13, Three Bells & Chicago P.D. Season 2, Episode 13, A Little Devil Complex

Major, emotional two-part resolution to firefighter Leslie Shay's death. On Fire, the department discovered new information about her death, making it criminal. This episode intensified as the Intelligence Unit sought the bomber who killed Shay. Both departments were deeply affected by this event, and it interprets One Chicago characters' emotional bonds.

10. Chicago Fire Season 2, Episode 20, A Dark Day &Chicago P.D. Season 1, Episode 12, 8:30 PM 

This crossover focused on a devastating explosion. The Fire episode described the horrific scene and Firehouse 51's heroic rescues. After the P.D. episode, the Intelligence Unit started searching for the bomber and stopping further attacks. This showed the seamless transition between chaos and calculated investigation.

11. Chicago Fire Season 3, Episode 21, We Called Her Jellybean, Chicago P.D. Season 2, Episode 20 The Number of Rats & Law & Order: SVU Season 16, Episode 20, Daydream Believer

This was a major three-part series about a Chicago-New York serial killer. The P.D. part investigated with the Intelligence Unit and Olivia Benson's team joined the killer hunt in SVU.

12. Chicago Fire Season 3, Episode 7, Nobody Touches Anything & Chicago P.D. Season 2, Episode 7, They'll Have to Go Through Me, & Law & Order: SVU Season 16, Episode 7

Another three-show event, this involved a difficult case that required police and fire department expertise and connected to SVU's New York expertise. The Dick Wolf style relies on cases logically jumping between cities and shows, and this event proved it.

13. Law & Order: SVU Season 15, Episode 15, Comic Perversion & Chicago P.D. Season 1, Episode 6, Conventions

First P.D.-SVU crossover. Benson's team first handled a Chicago-related sexual assault case in New York. The P.D. episode showed the Intelligence Unit helping Benson find a serial killer, suggesting connections between the cities.

14. Chicago Fire Season 1, Episode 23, Let Her Go

A fire that killed a Firehouse 51 team member was investigated by Hank Voight and the Intelligence Unit in this Chicago P.D. backdoor pilot. By showing the often rocky relationship between Casey and Voight, this episode set up a psychological base of the franchise.

15. Chicago Fire Season 3, Episode 19, I Am the Apocalypse

A massive gas leak brought many victims to Gaffney Medical Center, introducing Dr. Will Halstead and the hospital. The episode creates the way for the spinoff's medical drama with a hostage situation.

All the Chicago shows are available to stream on NBC.