Tony Award winner Will Brill stars in "The Musical," a darkly comic Sundance premiere now rolling out in limited theatrical release, about a middle school theater teacher who stages a student musical about the 9/11 terror attacks — complete with original music and cardboard Twin Towers ablaze — to sabotage a rival.

"You rarely see a movie now where the big question is, 'How the fuck did this get made? Who let them do this?'" Brill told Variety over lunch at Canter's Deli in West Hollywood.

Brill plays Doug, a nebbish teacher smitten with his colleague Abigail. When she takes up with the school principal — a smug "Chad" played by Rob Lowe — Doug secretly mounts his inflammatory musical, starring his earnest young students, to derail the principal's bid for a blue ribbon prize from the school district. Brill and director Giselle Bonilla, he argues, pull off the impossible: a broadly comic look at obsession and bitterness, softened by a cast of winning kids.

Brill drew on his own childhood in student theater. He started at age six, appearing in "The Velveteen Rabbit." "I remember distinctly the auditions and the chaos and the friendships built — and the gunning for the same roles and never getting them," he said. "A lot of my comedy specifically comes from never getting cast as the leading man in anything. I was always the kid playing the old man or having to do funny voices. I was the badger in 'The Wind and the Willows' and the king in 'Cinderella.'"

The revenge plot, he insists, is universal. During a marketing push for the film, the makers asked strangers, "What is the pettiest thing you've ever done?" Brill recalled his own answer: in his sophomore year of college, he told a girl he'd been flirting with that he had a girlfriend back home — a lie. "My character in 'The Musical,' Doug, is so obviously a villain," Brill said. "There are people who will watch this movie and say, 'I can't get behind this because he's so wretched.' But I think most people will realize, 'He's doing the thing that all of us have fantasized about, and none of us have the cojones to do.'"

Screenwriter Alex Heller, Brill said, watched "The Producers" and "Election" before writing, then typed "Fuck it: 9/11 musical" into his notes app. Some of the film's child actors had even performed plays about 9/11 at school. Brill argues that putting the concept in children's hands "defangs it": the in-film audience is horrified, but also gasps and cracks up.

The lead role nearly eluded Brill. The film's proof of concept starred an Instagram-famous performer, and Bonilla had previously offered the part to Andrew Garfield and Adam Driver; she initially offered Brill the principal's role that eventually went to Lowe. Ten days before shooting began, the previous leads dropped out and Gillian Jacobs was cast. A producer's coincidental meeting with Rob Lowe sealed the deal — Lowe gave him the script and "he was obsessed," especially upon learning the shoot would take place in Los Angeles.

Lowe proved a gifted improviser, Brill said, though two of his best lines were cut: "You turned the gymnasium into Ground Zero. Are you fucking mental?" and "My brother was a first responder … in Burbank."

Despite a strong Sundance premiere, distributors hesitated to close a deal. Brill has made peace with that. "I have definitely come to a reconciliation that my taste is not everyone's taste, and my taste is especially not corporate America's taste," he said, echoing Andy Richter's critique of the entertainment industry's corporatization. He and Lowe point to "The Book of Mormon" as a precedent for inflammatory material that still found love for its targets — evidence, Brill suggests, that audacious work can still get made, even when nobody wants to be the one who greenlit it.