Everything to Know About the One Chicago Crossovers, Including This Month's New Event

One Chicago is coming back. Not only do Chicago Med, Chicago Fire, and Chicago P.D. return from their winter breaks on Wednesday, Jan. 8 for regular episodes, but the three shows are crossing over once again, for the first time since before the pandemic.

So, as we prepare for the first One Chicago crossover in five years, it's time to brush up on the history of the NBC series' joint events as well as get all the details we know about the upcoming crossover, including the One Chicago crossover release date. 

When is the new One Chicago crossover airing?

The three-hour crossover is set to air on Wednesday, Jan. 29 beginning at 8/7c, as always. However, due to the nature of the story, the order that the shows usually air will be switched up. Instead of Chicago Med kicking off the night as it always has, the crossover will start with Chicago Fire, followed by Chicago Med at 9/8c, with the block ending with Chicago P.D. at 10/9c.

What happens in this crossover?

All we know about the crossover right now is NBC's official logline, which says: "When a gas explosion rocks a high-rise, Chicago's first responders come out in force to rescue hundreds of civilians. It's the calamity beneath the surface, however, that sends our heroes on a race to save 40 people trapped deep underground, including two of their own." What sets up that particular emergency is still unknown, and what characters' lives will be in the balance is a matter of guessing. 

More on One Chicago and NBC:

• Everything to know about Chicago Fire Season 13
• Everything to know about Chicago P.D. Season 12
• Everything to know about Chicago Med Season 10
• NBC winter TV schedule: Here's when your favorites return

How the shows relate to each other

The shows exist in the same universe. They're all set in the same city — Chicago! — except, unlike other shows set in the same town that are unrelated to each other, these shows do take place in the same version of their city. That means that when the paramedics from Chicago Fire take their victims to the hospital, that hospital is actually Chicago Med, and when the firefighters on Chicago Fire require a cop, they actually call on the cops from Chicago P.D.

In the early days of the shows, that made for many "mini-crossovers," with characters from all three different shows crossing over for cameos occasionally. The pandemic mostly put a stop to that, though there have been some recent cameos. For example, Chicago Med's Sharon Goodwin (S. Epatha Merkerson) appeared in Episode 4 of Chicago Fire's thirteenth season when Violet (Hanako Greensmith) needed advice about the suspension of her paramedic license, and Chicago P.D.'s Kevin Atwater (LaRoyce Hawkins) appeared in Chicago Med's sixth episode of Season 10 as threats against Goodwin were being investigated.

Existing character connections between the One Chicago shows

The one surviving connection in the One Chicago universe is the marriage between Chicago Fire's Mouch (Christian Stolte) and Chicago P.D's Sergeant Platt (Amy Morton), who met in Season 2 of Chicago Fire, during Chief Boden's (Eamonn Walker) wedding, and got married in Season 4 of the same show. Mouch is still a series regular on Chicago Fire, while Platt is still a series regular on Chicago P.D.

Previous One Chicago character connections

The One Chicago universe was built on connections between the shows, but as cast members from Chicago Fire, Chicago Med, and Chicago P.D. have come and gone, many of those relationships don't exist on-screen anymore. 

Early in their existences, the shows weren't strangers to family affairs. Chicago Fire had Gabriela Dawson (Monica Raymund) and Chicago P.D. had Antonio Dawson (Jon Seda), Gabriela's brother, but both have since left their respective shows. Meanwhile, Chicago P.D. had Jay Halstead (Jesse Lee Soffer) and Chicago Med had his brother, Will Halstead (Nick Gehlfuss), but again, both actors have moved on to other projects. For a while there, Chicago Med had both April (Yaya DaCosta) and Noah Sexton (Roland Buck III), but it's been years since they both left.

To keep things spicy, characters from different Chicago shows have also dated. Chicago Fire's Kelly Severide (Taylor Kinney) famously dated Chicago P.D.'s Erin Lindsay (Sophia Bush) during the first few seasons of both shows, and he was a childhood friend of April Sexton (and the two even shared a kiss, though they never really dated). Oh, and Antonio Dawson dated Sylvie Brett (Kara Killmer). Neither of those relationships really lasted, though. It's hard to keep a relationship going between two shows. Unless you're Mouch and Platt, that is.

Crossovers featuring all three One Chicago shows

There have been a trio of full three-way crossover events between Chicago Fire, Chicago Med, and Chicago P.D. so far, with the upcoming crossover airing on Jan. 29 set to be the fourth. In Chicago Med's first season, the three shows crossed over in a two-night event on Jan. 5 and 6, beginning when Herrmann (David Eigenberg) was stabbed in Chicago Fire Season 4, Episode 10, "The Beating Heart," and continuing in the second hour set during Chicago Med Season 1, Episode 5, "Malignant," in which Rhodes (Colin Donnell) tried to save Hermann. The event concluded the next night with Chicago P.D. Season 3, Episode 10, "Now I'm God," which saw a doctor connected to Voight (Jason Beghe) investigated.

After that, we didn't get another three-way crossover until three years later. Chicago Fire's Season 7, Episode 2, "Going to War" kicked off a crossover that was mostly about the Halstead brothers and their father, a storyline that continued in Chicago Med Season 4, Episode 2, "When to Let Go," and then in Chicago P.D. Season 6, Episode 2, "Endings."

Proof that One Chicago got bigger and better with crossovers came with its most recent three-way crossover, which kicked off with Chicago Fire Season 8, Episode 4, "Infection: Part I," which led into Chicago Med Season 5, Episode 4, "Infection: Part II," and ended with Chicago P.D. Season 7, Episode 4, "Infection: Part III." As the names implies, it's all about a deadly virus affecting the population of Chicago and it ironically aired the year before the pandemic.

Remember Chicago Justice? The short-lived drama exploring the legal system in Chicago was also part of a three-way crossover in its pilot episode that aired on March 1, 2017. The crossover, about an intentionally set warehouse fire that killed dozens of people, began on Chicago Fire's Season 5 episode "Deathtrap," continued on Chicago P.D.'s Season 4 episode "Emotional Proximity," and concluded with the premiere episode of Chicago Justice, "Fake." 

Crossovers featuring two One Chicago shows

There have been quite a few crossovers featuring just two of the One Chicago shows — and some even featuring appearances by characters from other Dick Wolf shows, mostly notably Law & Order: SVU. Those include the following:

• Chicago Fire Season 2, Episode 20, "A Dark Day," and Chicago P.D. Season 1, Episode 12, "8:30 PM"
• Chicago Fire Season 3, Episode 7, "Nobody Touches Anything," and Chicago P.D. Season 2, Episode 7, "They'll Have to Go Through Me" (this crossover also includes Law & Order: SVU Season 16, Episode 7, "Chicago Crossover")
• Chicago Fire Season 3, Episode 13, "Three Bells," and Chicago P.D. Season 2, Episode 13, "A Little Devil Complex"
• Chicago Fire Season 3, Episode 21, "We Called Her Jellybean," and Chicago P.D. Season 2, Episode 20, "The Number of Rats" (this crossover also includes Law & Order: SVU Season 16, Episode 20, "Daydream Believer")
• Chicago Fire Season 5, Episode 9, "Some Make It, Some Don't," and Chicago P.D. Season 4, Episode 9, "Don't Bury This Case"
• Chicago P.D. Season 5, Episode 16, "Profiles," and Chicago Fire Season 6, Episode 13, "Hiding Not Seeking"
• Chicago Fire Season 7, Episode 15, "What I Saw," and Chicago P.D. Season 6, Episode 15, "Good Men"
• Chicago Fire Season 8, Episode 15, "Off The Grid," and Chicago P.D. Season 7, Episode 15, "Burden of Truth"

Backdoor pilots

There are also technically two episodes that aren't crossovers, but that set up the characters from the other two shows — the backdoor pilots for both Chicago P.D. and Chicago Med. Both are Chicago Fire episodes, one in Season 1, Episode 23, titled "Let Her Go," and one in Season 3, Episode 19, titled "I Am the Apocalypse." The first sets up Chicago P.D. and the second one sets up Chicago Med. Chicago Justice was also introduced as a backdoor pilot in the Chicago P.D. Season 3 antepenultimate episode "Justice."