Chicago P.D. Showrunner Compares The New One Chicago Event To The 'Infection' Three-Parter, And Now I Want To Rewatch The 2019 Crisis

Ruzek, Platt, and a bunch of cops in the Chicago Fire leg of One Chicago's 2025 crossover
(Image credit: Peter Gordon/NBC)

It's been a long time since One Chicago fans have been able to look forward to an epic three-part crossover, but the 2025 TV schedule is on the verge of delivering. The "In the Trenches" event brings the heroes of Chicago P.D., Chicago Fire, and Chicago Med together to deal with an explosion and a subway collapse, with more than one hero in very real danger.

The plot doesn't sound too similar to 2019's "Infection," but when I spoke with P.D. boss Gwen Sigan, she compared the 2025 event to what went down more than five years ago, and it put me in the mood to rewatch "Infection" after "In the Trenches."

How The Crossovers Compare

Gwen Sigan is credited with the teleplay for the Chicago P.D. leg of "Infection," so when I spoke with her after her comments about the Burzek relationship, I had to ask: how does "In the Trenches" compare to the last time that One Chicago came together back in 2019? The P.D. showrunner shared:

Gosh, that was a big one too. That definitely was. I think the scale is probably similar, if you look at just the incident itself. Obviously [for] these things, you need an incident that is going to be able to sustain you for three hours, and so it's gotta be pretty big, and it's gotta keep changing and keep morphing. I think this one, just the way that the writers worked together, they really broke it almost all together. Because of that, I will say this one feels very interwoven.

While I loved the "Infection" crossover and definitely am not mad to be in the mood to rewatch it with my Peacock subscription, I can agree that it didn't feel entirely "interwoven," particularly with the P.D. episode feeling distinctly like P.D. since the Med and Fire characters could only do so much to take down the bad guys. Sigan went on:

It feels very much like you're gonna forget what hour you're in. You're not gonna quite know, like, 'Oh, wait, I'm in a P.D. hour, but these are all Fire characters.' You're just along for the ride. It feels like a movie. It feels like the story is just sort of moving it. So I will say that I think feels a little different because of just how cohesive it is. It's really a movie.

The promo certainly has the characters mingling with each other, to the point that Chicago Med showrunner Allen MacDonald was surprised that so much was revealed. For her part, Chicago Fire boss Andrea Newman previewed the scale of the inferno for the event, saying that flames shooting up "three stories" was "freaking out the neighbors."

The "Infection" storyline of course had a grand scale insofar as the first responders had every reason to believe that a flesh-eating infection could be spreading throughout the Windy City, but it wasn't quite explosive in the way that "In the Trenches" will be. Still, talking about the new one reminded me of what was great about the last one, and I may have something to revisit sooner rather than later.

But if "In the Trenches" is going to be more cohesive than "Infection," how will P.D.'s Intelligence Unit be incorporated this time around?

How Chicago P.D. Will Be Incorporated More

While the promo confirms that Ruzek is one of the two One Chicago characters trapped underground (with Fire's Stella Kidd as the other) and that Platt will be in a life-or-death state, there was still the question of how the characters who aren't usually rushing into fires or administering aid will be key to the storyline. Gwen Sigan shed some light, saying:

Right off the bat, you've got the first responder element that they're coming there to help secure the scene and make sure the safety of everyone involved, and make sure everything is safe for the firefighters to get in there and that type of thing. And then the story does quickly shift when we realize that this was an intentional event and this was a crime, and because of that, we then become very integral to the plot and to finding out who is responsible for this, and also tracking down those offenders in time. There's a ticking clock that presents itself, and we need to track these people down in order to basically save quite a few lives. And so it becomes a great engine for us to then keep the ball going through the third hour.

Of the three One Chicago showrunners, Andrea Newman wasn't able to visit the Fire set and Allen MacDonald only made it in time for the last scene of Med's episode. So, was Gwen Sigan on set for much of the P.D. leg of the three-parter? She shared:

I was! Not for the first incident, but certainly for the third hour, in our hour, I was on set. It was fun. I mean, these things are big. You get to be there and you get to see what all three shows were able to build and just accomplish. The feat of that alone with the time frame. Us being a television show, we shoot really fast. We shoot 22 [episodes] a year. So the fact that our crews are able to do this is pretty incredible, and that it looks the way that it looks. That alone was really neat, to just get to see the sets that they built.

All in all, it sounds like the whole One Chicago team went above and beyond to make "In the Trenches" worth the wait after "Infection" back in 2019. Be sure to tune in to NBC on Wednesday, January 29 to check out the action, starting with Fire at 8 p.m. ET in a time slot switch, followed by Med at 9 p.m. ET, and ending with Chicago P.D. at 10 p.m. ET. The order was the same for "Infection," which you can stream with a Peacock subscription now.

Laura Hurley
Senior Content Producer

Laura turned a lifelong love of television into a valid reason to write and think about TV on a daily basis. She's not a doctor, lawyer, or detective, but watches a lot of them in primetime. CinemaBlend's resident expert and interviewer for One Chicago, the galaxy far, far away, and a variety of other primetime television. Will not time travel and can cite multiple TV shows to explain why. She does, however, want to believe that she can sneak references to The X-Files into daily conversation (and author bios).

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