TORONTO—There’s a general rule regarding meeting comedians in person. It stipulates that those who make their living as a result of being funny aren’t actually anything like the goofballs that they play onscreen. Steve Carell is no exception to this rule. Speaking to media in a hotel at the Toronto International Film Festival with his Foxcatcher costars Channing Tatum and Mark Ruffalo, Carell is decidedly sombre. It’s not a surprise, really, given that Carell’s performance as troubled heir John Eleuthère du Pont has him donning a prosthetic nose and generally hanging in the balance between creepy and downright psychotic.

Foxcatcher (opening Friday [November 28]) revolves around the true story of du Pont’s desire to win an Olympic gold medal in wrestling by building a training facility and bringing in Mark (Tatum) and Dave (Ruffalo) Schultz to train and coach. Framed by director Bennett Miller (Capote, Moneyball ) as an intense, thoughtful thriller that builds and builds until it explodes, the film is slow-paced and absolutely hinges on the ability of its main actors to deliver. And, yes, the former Daily Show correspondent and 40-year-old virgin delivers.

The film debuted to rave reviews on the festival circuit—Foxcatcher has received rave reviews wherever it’s opened, including the Vancouver International Film Festival—and won best-drector honours for Miller at Cannes. So the question just had to be asked, as indeed it is at one point during the interview: “This film has had so much early success, why don’t you guys look a little happier?”

“That’s a tricky thing, because you don’t want to be cavalier about the success of the film within the darkness and tragic size of the story,” Carell responds, still barely breaking a smile. “That’s all. But we are. We’re mutedly happy.”

If you think it’s strange to see Carell being so unabashedly dour, you’re not alone. After all his years mugging for the camera with that awkward smile as Michael Scott on The Office, this role will no doubt go down as a career game-changer. But look a little closer and there’s something deeper and darker in his résumé. He worked with Woody Allen in 2004’s Melinda and Melinda, albeit in a bit part, and portrayed a gay man on the edge of suicide a couple of years later in Little Miss Sunshine. Yes, he sandwiched those roles with characters like vapid, hilarious Brick in Anchorman and lame Andy in the aforementioned Virgin, but the urge to do more meaningful work has always been there, and it’s certainly never come to the surface quite like this.

“I’ll be honest, the whole thing is almost a blur to me,” Carell says, with a sense of wonderment. “From beginning to end, once we got to Pittsburgh [where Foxcatcher was filmed], the experience is sort of a blur. I don’t remember very much specifically about what the process was and what we were doing and where we were and what we talked about or even how painful it was. I thought we were immersed in something and a few months after it came out, I got to hang out with these guys when we started doing press. But until then, there was a tone, there was definitely a weight that was hanging over the entire experience, but specifically, it’s really hard for me to recount. I don’t ever remember having that sort of experience before, and it was exhilarating.”

In a separate interview, when asked about his casting of Carell, Miller replied: “The fact that he’s not an obvious choice is what made him an obvious choice, because he does what du Pont does, which is the unimaginable. Nobody saw du Pont doing what he did, nobody thought du Pont had that in him, and so it had to be an actor who you considered benign but had this whole other thing, which was not hard to see when I met him and talked to him. He revealed a willingness to exhibit these qualities that not many comics have, I must tell you.”

The only time anyone cracks a smile during the interview is a direct result of Carell being so goddamned creepy. “He would come in and no one would talk to him,” Ruffalo reminisces about the way Carell physically transformed into du Pont. “It was strange. You’d say, ‘Hi, Steve,’ and he’d say, ‘Hello.’ And then, ‘Okay, I’m going to run away now. I don’t know what to say to that person.’ ”