Chicago P.D. stars on the difficulties of filming the 200th episode

At this point on Chicago P.D., Adam Ruzek (Patrick John Flueger) and Kim Burgess (Marina Squerciati) have been through a lot, both as members of the Intelligence Unit and as one of the show’s longest-running will-they-won’t-they couples.

And as the series hit its 200th episode Wednesday, it focused in on, specifically, Kim’s trauma. At the end of the NBC drama’s eighth season, Burgess was kidnapped and shot multiple times, coming about as close to death as she ever had. Now, in season 10, she still hasn’t fully confronted her trauma, which was the focus of the 200th hour. First, a car backfiring caused a panic attack at home. Then, as Burgess and Ruzek boarded a busy subway car to find a shooter, she found herself once again immobilized in fear.

The big episode was one that Squerciati didn’t have a ton of time to prepare for. “When it’s something big, they do give you a heads-up, so I’m not totally in the dark, but I got the script the night before,” the actress tells EW. “Without the words, you can’t really track the journey.” As for the filming of the episode, Flueger and Squerciati found themselves in the middle of a subway station for some of the scenes. “The green line and the brown line were right to our right just zooming by,” Flueger says. “It was insane.” He adds, “When the train on the show was static, we were actually in a tunnel on a now-defunct line. When the train was moving, we’ve got four or five guys just manning two-by-fours under the train, pulling on them.”

If that didn’t complicate the shoot enough, Flueger recalls, “There were no bathrooms in the tunnel. One of the guest stars, no joke, used a coffee cup.” The difficult scenes didn’t end there for Squerciati, who spent some of the episode in a well. “I was in a pool for 12 hours,” she says. “So in the well scene, it’s a big pool and then they built a shaft in the middle and it goes up really high. So there’s no way to get me to the top to shoot me dry. So I’m in fishing waders and then literally on the shoulders of two men being carried through this pool so I can be dry, climb up the ladder, take off the waders, and then climb down dry. So I only got one take of that.”