The Good Doctor‘s fall finale (ABC, Monday at 10/9c) is technically the medical drama’s first Christmas episode — and yet, there are no presents to be found. Instead, the doctors of San Jose St. Bonaventure receive a lump of coal in the form of a deadly airborne virus that forces the ER to be placed under quarantine.

“When I first got the script, I was like, ‘What?!’ It was quite the page-turner,” series star Christina Chang tells TVLine. “Everybody just falls apart… everything is so dramatic.”

Fans of Chang’s Dr. Audrey Lim will at first be especially happy with the episode, which finds Lim front and center as she takes charge of a dire situation.

“Lim’s dedication to the emergency room is really felt in this episode,” Chang says. “Even given what happens throughout, no matter what, she’s saving lives,” and she’s doing so to the best of her ability, despite the circumstances. “She’s always calm, she’s always collected… so she’s in her element. She’s not really knocked off her balance at any point. There’s maybe a glimmer of that when she discovers something that’s happened,” but otherwise, “she has her wits throughout.”

And that “something,” which ABC’s promo department has already let slip, is that Lim is eventually among the infected.

“I was shocked when I saw that [commercial],” Chang admits. “I thought that was one of the big reveals, but it’s also maybe a reason to watch.”

And just how concerned should fans be? “They should be worried,” Chang says. “She gets the same virus that is killing [her patients],” and it’s spreading fast.

Are you on the edge of your seat waiting for The Good Doctor‘s fall finale? Watch (or rewatch) the promo for 2×10 below, then hit the comments with your reactions!