If you put it in a movie, nobody would believe it. “I saw him while I was writing the script and Connor had no idea I was there,” says Stephen Dunn, the 27-year-old filmmaker behind Closet Monster. “I was, like, just creeping around.”

“I probably saw him and thought, ‘Oh, just another 20-something trying to write a script,’ ” interjects the film’s star, Connor Jessup, joining his director on a call to the Straight from Toronto. “It wasn’t until much later, I guess the next year, that I got the script and he told me the story.”

The story is this: Connor Jessup was regularly hanging around at the University of Toronto’s stately Hart House, playing board games with friends and taking a breather from his day job as one of Canada’s most exciting young actors. (If you’ve seen the 2012 film Blackbird, you’ll know what Jessup is capable of.) Dunn happened to use the same location to plot his feature-film debut: an antic coming-of-age tale about a closeted gay youth, his broken home, his casually homophobic father, and his viscerally realized nightmares. But he allows that the movie star in the far corner might have provided some inspiration.

All this serendipity has its payoff in the finished film, opening in Vancouver on Friday (July 22). While Closet Monster bursts with ideas, employing wild and unruly mood shifts that include the leap from a traumatic and hysterically lensed violation-by-rebar to the introduction of a talking hamster (voiced, naturally, by Isabella Rossellini), Jessup provides its calm middle. “Connor brought a seriousness to this role amidst its world of fantasy and horror and fear,” is Dunn’s assessment. “He was so grounded. It was no longer just me and my computer. It was purely collaborative.”

For his part, Jessup claims everything he needed was established back at Hart House. “I’ve been in things where you’re like, ‘Well, here’s a shapeless mess. How do I pull this into something that resembles not just a person but a person who’s going somewhere?’ But this character was so fully formed and so fully realized in the script that I felt like even if I did the most rote, basic, perfunctory performance, there’d still be a through line and there’d still be a movie.”

Jessup’s performance is anything but perfunctory, but it is understated, and beautifully so. Director Dunn name-checks Spike Jonze and the two big Davids (Lynch and Cronenberg) when he’s asked about his personal cinematic raves. Jessup replies to the same question with Yasujirō Ozu, Shohei Imamura, and “the golden age of Japanese cinema”. It’s tempting to wonder how much of that has influenced the 22-year-old’s uncanny mastery of stillness.

“To throw myself under a bus, it’s also a crutch,” he demurs. “Sometimes I watch myself and think, ‘Just fucking do something.’ But your flaws or your inhibitions or your shortcomings are just as much a part of your style as the things you can do well, so there’s a certain point where you have to embrace what your instincts are and follow that. When you work with a good director like Stephen, you’re supported and encouraged. It’s a liberating feeling.”