For more than a decade, NBC’s One Chicago universe has captivated viewers with its mix of high-stakes emergencies, personal drama, and deeply human storytelling. But if there’s one thing fans look forward to the most, it’s the epic crossover episodes that unite Chicago Fire, Chicago P.D., and Chicago Med (and in earlier years, Chicago Justice). These events raise the stakes to cinematic levels, blending action and emotion across the city’s firefighters, doctors, and police officers. If you’re new to the franchise — or simply looking for a refresher — here’s your guide to every must-watch One Chicago crossover episode.
1. “Infection” (2019, Three-Part Event)
This ambitious trilogy remains one of the franchise’s most unforgettable crossovers. Beginning with Chicago Fire, the story follows a deadly flesh-eating bacteria outbreak that spreads across the city. The crisis continues in Chicago Med as the doctors fight to save patients while searching for the cause. Finally, Chicago P.D. closes the event as the Intelligence Unit tracks down the source of the outbreak in a race against time. Equal parts thrilling and terrifying, “Infection” is a fan favorite.
2. “Justice” (2016, Fire/P.D./Justice Launch)
This crossover not only delivered a tense storyline but also introduced viewers to Chicago Justice. After a suspect in a fire is released, the case weaves its way through Chicago Fire and Chicago P.D. before landing in the courtroom. It’s a perfect example of how the One Chicago shows connect seamlessly while exploring different aspects of law and order.
3. “Don’t Bury This Case” (2017, Fire/P.D.)
When Kelly Severide (Chicago Fire) finds himself at the center of a vehicular manslaughter case, his world collides with Chicago P.D.. This crossover highlights both Severide’s vulnerability and the Intelligence Unit’s determination to uncover the truth. Emotional and character-driven, it’s one of the best smaller-scale crossovers.
4. “Deathtrap” (2017, Fire/P.D./Justice)
A devastating warehouse fire sets the stage for another multi-show event. Chicago Fire kicks things off with heartbreaking rescues, Chicago P.D. follows the investigation into arson, and Chicago Justice delivers the courtroom drama. This crossover is remembered for its emotional gut punches and the way it tested the resilience of Chicago’s heroes.
5. “When to Let Go” (2018, Med/Fire/P.D.)
Starting with Chicago Med, this crossover explores the aftermath of a high-rise apartment fire. Families are torn apart as doctors work tirelessly to save lives, while Chicago Fire and Chicago P.D. uncover the fire’s tragic origins. Deeply emotional, it’s a perfect blend of medical heroics and raw human drama.
6. Earlier Fire/P.D. Crossovers (2014–2015)
Before the official “One Chicago” brand existed, Chicago Fire and Chicago P.D. frequently crossed paths. Memorable moments include joint investigations into arson cases, gang wars, and personal entanglements that set the foundation for the massive crossovers fans enjoy today.
Crossover events showcase the heart of One Chicago: community, teamwork, and resilience in the face of overwhelming odds. They bring together fan-favorite characters in unexpected ways, often pairing unlikely allies while pushing each show’s storytelling to new heights. For viewers, it’s the ultimate payoff — seeing the interconnected lives of Chicago’s bravest on full display.
