The 10 best One Chicago crossovers, ranked

Chicago Med Chicago Fire Crossover
Chicago Med and Chicago Fire cast members join forces for a new episode of Med. Pic credit: Adrian S. Burrows Sr./NBCUniversal

Nearly a decade after it began with Chicago Fire, the One Chicago universe remains one of the most fascinating on television.

Each of the shows (Chicago Fire, Chicago PD, Chicago Med, and the short-lived Chicago Justice) connects seamlessly. It’s natural to see some of the Med doctors checking on an injured firefighter or the cops interviewing a witness at the hospital.

There are also the connections of the shows, such as how Chicago PD’s Jay and Chicago Med’s Will Halstead are brothers while fireman Mouch is married to cop Trudy. That’s not to mention the connections to Law & Order: Special Victims Unit and even CBS’ FBI series. 

Each season has brought at least one big crossover between the shows, whether a two-parter or spread across the three main series. There have been numerous since the shows began, but some have managed to stand out both for the excitement and for how they add more depth to the characters.

These are how the ten best One Chicago crossovers rank as a reminder of how this show is one of the best TV universes on the air. 

10. The Beating Heart (Season 4, Episode 10) / Malignant (Chicago Med Season 1, Episode 5) / Now I’m God (Chicago PD Season 3, Episode 10)

Chicago Fire/Chicago Med
Dr. Rhodes (Colin Donnell) tends to an injured Herrmann (David Eigenberg) on a Chicago Fire/Chicago Med crossover. Pic credit: NBC

What looks like a stand-alone emergency turns into a long-range case for Chicago Med’s first crossover appearance.

The Firehouse 51 team is rocked when Herrmann is stabbed and when his condition gets more serious, they and the Chicago Med doctors are at odds about his treatment.

Meanwhile, Cruz blames himself as Herrmann’s attacker was a former gang member he’d been mentoring. He thus goes out of his way to help police track the attacker.

The firefighters then attend a blaze caused by a woman seemingly attempting suicide. However, it appears to be murder, which leads to the discovery that several people have overdosed on chemotherapy despite not having cancer.

The police proceed to investigate, with Voight shocked that the doctor in question had treated Voight’s late wife. That gives him a personal reason to find out the truth. 

It’s a tough storyline yet also heartwarming with Mouch proposing to Trudy to create a greater bond between the shows and prove how well the units work together.

9. We Called Her Jellybean (Chicago Fire Season 3, Episode 21) / The Number of Rats (Chicago PD Season 2, Episode 20) / Daydream Believer (Law & Order: Special Victims Unit Season 16, Episode 20)

Law & Order SVU/Chicago PD
Erin Lindsay (Sophia Bush) and Olivia Benson (Mariska Hargitay) work together on the Law & Order: Special Victims unit Daydream Believer. Pic credit: NBC

This three-part storyline had major implications for the Chicago PD unit, especially Erin Lindsay (Sophia Bush).

It starts with Firehouse 51 (alongside troubled new member Chili) handling a blaze with a firefighter under suspicion for assaulting a woman. While he’s proven innocent, the hunt for the true assailant is on.  

That brings in the SVU team as the case matches one Benson worked on a decade before. The cops work together to discover the twisted Gregory Yates is on the prowl and kidnaps Lindsay’s protege, Nadia.

It comes together in a heartbreaking loss that sends Lindsay into a tailspin. While Yates is captured, the long-range implications would haunt Erin for a long while and make this the darkest of the various Chicago PD/Law & Order: Special Victims Unit teamings. 

8. Three Bells (Chicago Fire Season 3, Episode 13) / A Little Devil Complex (Chicago PD Season 2, Episode 13)

The One Chicago Dawsons
Gabriela Dawson (Monica Raymund) and brother Antonio (Jon Seda) work together on Chicago Fire. Pic credit: NBC

This two-parter brought together the teams to seek justice for a fallen friend.

A few episodes after the devastating loss of Shay, an arsonist indicates the fire that killed her was deliberately set. This has the team, especially Dawson, on a quest for the truth.

They’re soon targeting a troubled man (Robert Knepper) who enjoys using the aliases of other arsonists to cover his crimes.

When the initial investigation falters, Gabby Dawson reaches out to brother Antonio and the Intelligence Unit for help. But the arsonist is a twisted monster whose “games” include locking Dawson in a burning elevator before a wild final showdown.

It brings up some tension between the PD and firefighters, yet it is still good to see Antonio helping his sister avenge her friend and Firehouse 51 honor their late comrade.

7. Off The Grid (Chicago Fire Season 8, Episode 15) / Burden of Truth (Chicago PD Season 7, Episode 15)

Screenshot from Chicago Fire.
Brian Geraghty as Sean Roman in Chicago Fire. Pic credit: Adrian Burrows/NBC

This two-parter brought back a former Chicago PD cast member for the worst homecoming imaginable.

After years away, former cop Sean Roman returns to Chicago, seeking help from the firefighters to find his missing sister. He claims to be aiding the Intelligence Unit only for Severide to discover they had no idea Roman was in town.

Roman ends up shooting a man as his sister was tied in with the dealer dispensing deadly drugs across Chicago.

The search has tension between Roman and his former partner (and lover) Kim Burgess as Roman’s actions can jeopardize the team’s drug investigation. The fact that he thinks his sister was involved in the drug dealing doesn’t help.

It leads to a tragic turn for Roman and he crosses the line seeking justice on his own terms. His farewell closes the chapter on the character while showing how the two teams have different approaches to keeping the city safe. 

6. Profiles (Chicago PD Season 5, Episode 16) / Hiding Not Seeking (Chicago Fire Season 6, Episode 13)

Chicago PD 100th episode
Trudy (Amy Morton) aids the injured with Voight (Jason Beghe) on Chicago PD’s 100th episode. Pic credit: NBC

This story (which was also Chicago PD’s 100th episode) starts on a light note as the Intelligence Unit gets a kick seeing Trudy on TV. Unfortunately, the humor ends when a bomb ravages the studio on air. 

While Trudy rescues a civilian, the Firehouse 51 crew contains the blaze while the cops handle who’s responsible. It leads to a dark case involving a disgraced reporter seeking revenge for his life ruined over a fake story.

Dawson and Sylvie Brett are sent on a dangerous undercover operation which causes a clash of the two squads. Thankfully, they’re able to come together to catch the bomber before it gets worse. 

It’s a good celebration of Chicago PD’s long run while showcasing how well the two squads work together. 

5. Dark Day (Chicago Fire Season 2, Episode 20) / 8:30 PM (Chicago PD Season 1, Episode 12)

Chicago Med backdoor pilot
Amanda Righetti and Marina Squerciati in the crossover pilot for Chicago Med. Pic credit: NBC

The first crossover of Chicago Fire and Chicago PD also introduced Chicago Med (albeit in a different form than the show we know today). 

While attending a charity race at the hospital, Dawson and Casey are caught when a bomb ravages the place. Burgess’ niece is among the injured as she worries about the responsibility of her health.

That’s enough to get Voight to override the FBI in taking the lead on the case, especially when it’s indicated this is just the first target by a radical out to make both cops and firefighters pay for a family tragedy.

Shay gets a severe injury from handling the rescue while the cops are tracking who’s responsible. The firefighters aid them in a race to stop another bomb from going off. 

While none of the Chicago Med characters fans we’ve come to love manage to show up in the episodes, this is important as the first major crossover of the One Chicago universe and set the stage for more team-ups down the line. 

4. Nationwide Manhunt (Law & Order: Special Victims Unit Season 17, Episode 14) / The Song of Gregory William Yates (Chicago PD Season 3, Episode 14)

Chicago PD/SVu
Hank Voight (Jason Beghe) works with Olivia Benson (Mariska Hargitay) on a Chicago PD/Law & Order: Special Victims Unit crossover. Pic credit: NBC

The sequel to the previous Chicago PD/Law & Order: Special Victims Unit storyline allowed the Intelligence Unit to finally get their justice. 

When Gregory Yates escapes from prison, Erin and Antonio head to New York to help the SVU team in the manhunt. Naturally, Erin is out for payback which can jeopardize her job.

The chase returns to Chicago with Yates kidnapping another woman and playing a game of cat-and-mouse with the cops. It builds to a final confrontation with Erin that someone doesn’t walk away from.

Another strong team-up of the cops allowed Erin to exorcise a deadly demon of her past. 

3. Deathtrap (Chicago Fire Season 5, Episode 15) / Emotion Proximity (Chicago PD Season 4, Episode 16) / Fake (Chicago Justice Season 1, Episode 1)

One Chicago crossover
Olinsky (Elias Koteas) deals with a horrible loss on the One Chicago crossover Deathtrap. Pic credit: NBC

While Chicago Justice only lasted one season, it did take part in this dark storyline. 

It opens with the firefighters answering a warehouse blaze where someone locked in dozens of teenagers to suffer. The case becomes personal for the Intelligence Unit as Olinsky’s daughter is one of the victims. 

The scene of him forced to say goodbye to her is one of the most tear-jerking of the series. For once, Voight is the voice of reason trying to keep a vengeful Olinsky from crossing the line bringing in the guilty party.

It paid off in the premiere of Chicago Justice as Stone has to prosecute the accused arsonist who has a wicked defense while the city is out for blood. That has Antonio (now working for the D.A.’s office) forced to question his old unit on their methods.

It showed that, in their own way, the prosecutors’ job was as dangerous as any of the other Chicago shows. 

2. Going To War (Chicago Fire Season 7, Episode 2) / When To Let Go (Chicago Med Season 4, Episode 2) / Endings (Chicago PD Season 6, Episode 2)

One Chicago Halsteads
Will Halstead (Nick Gehlfuss) and brother Jay (Jesse Lee Soffer) are at odds in a One Chicago crossover. Pic credit: NBC

This saga brought some dramatic developments for Stella Kidd and the Halstead brothers. 

Firehouse 51 is quick on the scene when a 25-story apartment building is caught in a huge blaze. Jay and Will Halstead’s father is one of the residents, while Stella is badly injured.

While Stella fights for her life and Otis deals with his own health scare, the Halsteads are at odds when their father takes a downward turn, leading to a stunning loss.

The final part has the cops discovering the fire was set to cover up a human trafficking ring. As they hunt the guilty party down, Jay wrestles with his loss, which can affect his judgment. 

While Stella turned out okay, the Halsteads were never quite the same after this powerful storyline. 

1. Infection (Chicago Fire Season 8, Episode 4 / Chicago Med Season 5, Episode 4 / Chicago PD Season 7, Episode 4)

One Chicago
The One Chicago teams deal with the Infection crossover. Pic credit: NBC

It may be a bit harder to watch today, but this thrilling three-parter gave the three teams their most terrifying case ever.

It all starts with the firefighters discovering a victim of a deadly flesh-eating bacteria. What appears to be a minor case soon spreads to others across the city, with the cops and doctors soon called in.

Eventually, it’s discovered this isn’t a natural cause but a twisted doctor trying to teach a “lesson” to the world by exposing the city to a bioengineered virus. The cops have to race against time to find him while the doctors work on a cure.

The shots of a deserted Chicago are chilling, and drama was at an all-time high with Upton exposed to the virus herself. It also shows the sad realism of people panicking amid this outbreak. 

While handled in the end, the last major One Chicago crossover remains one of its most gripping. 

Chicago Fire Seasons 1-10, Chicago PD Seasons 1-9, Chicago Med Seasons 1-7, and Law & Order: Special Victims Unit Seasons 1-23 are all streaming on Peacock. 

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