It's a "One Chicago" event you do not want to miss.

For the first time in five years, “Chicago Med,” “Chicago Fire” and “Chicago P.D.” are crossing over on Jan. 29.

Described as a “three-hour action movie” by Anastasia Puglisi, Wolf Entertainment executive vice president and co-executive producer of the "One Chicago" series, the stars from Firehouse 51, Gaffney Medical, and the Intelligence Unit will reunite to save the day — and their own.

The last time the three NBC dramas had a crossover event was in 2019.

Read below for everything to know about the "One Chicago" three-episode crossover, including how to watch.

What time is the ‘Chicago Med’, ‘Chicago Fire’ and ‘Chicago P.D.’ crossover?

The One Chicago crossover will air on Wednesday, Jan. 29, starting at 8 p.m ET/PT and ending at 11 p.m.

There's a shift in show order for the crossover event. “Chicago Fire” will air first at 8 p.m., followed by “Chicago Med“ at 9 p.m., with “Chicago P.D.” concluding the event at 10 p.m.

How to watch the ‘One Chicago’ crossover episodes

The three-hour "One Chicago" crossover will first air on NBC and then be available to stream the following day, Jan. 30, on Peacock.

What is the ‘One Chicago’ crossover about?

The show’s official description lay out the plot: “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.”

In the first promo released on Jan. 22, “Chicago Fire” Battalion Chief Dom Pascal (Dermot Mulroney) informs his crew of the accident.

“Possible gas explosion, 50 to 60 victims,” he says, followed by Lt. Stella Kidd (Miranda Rae Mayo), who appears underground helping people on the train.

“Stay on the train until the ground settles,” she tells victims, while Lt. Kelly Severide (Taylor Kinney) yells, “People are still on that train, including my wife.”

With many of their own colleagues stuck in the rubble, Kidd tells Adam Ruzek (Patrick Flueger), who is also stuck underneath, “We’re running out of air.”

As other “Med” and “P.D.” characters face their own troubles, the promo ends with Pascal saying, “Kidd, do you copy?” He receives no response.