The Sundance Film Festival raised the curtain on Theater Camp Saturday afternoon, presenting the world premiere of the feel-good mockumentary made by four best friends, Ben Platt, Noah Galvin, Molly Gordon and Nick Lieberman.

The audience inside Park City’s Eccles Theatre gifted the showing with a generous and heartfelt standing ovation and saved another for the surprise musical performance that followed the final credits, a rarity for a fest screening. The brief musical ditty featured eight young actors belting out a medley of tunes written for the movie’s musical finale titled Joan, Still. When they had taken their final bow, the crowd cheered and applauded like one would for a Broadway performance.

Theater Camp opens with a scene that sets up the rest of the film: the beloved founder of a run-down theater camp, played by Amy Sedaris, suffers a seizure due to a strobe light in a high school production of Bye, Bye Birdie. As summer rolls around again, kids are gathering from all over to attend her scrappy camp in upstate New York, amusingly called AdirondACTS.

Her clueless “crypto-bro” son Troy, played by Jimmy Tatro, is tasked with keeping the thespian paradise running while being forced to navigate the drama with the camp’s staff, played by Platt, Gordon, Galvin, Ayo Edebiri, Nathan Lee Graham and Owen Thiele, as they mount a production in Joan’s honor. Minari breakout Alan Kim also has a scene-stealing role as a wannabe talent agent, and Patti Harrison plays a business development exec with ulterior motives.

The film also boasts big-name producers from Gloria Sanchez Prods., Picturestart and Topic Studios, including Will Ferrell, Jessica Elbaum, Erik Feig, Samie Kim Falvey, Julia Hammer, Ryan Heller, Maria Zuckerman, Galvin, Gordon, Lieberman and Platt. Theater Camp is one of the titles up for distribution so today’s debut will likely fuel sales talk thanks to the audience’s warm embrace.

Gordon and Lieberman teamed to make their feature directorial debut on the film and during the brief Q&A that followed the premiere (and performance), she explained how that came to be.

“It literally came out of us just wanting to make something with our friends. I met Ben when I was 3 years old. I’m going to cry because this is very overwhelming. I was in love with him, and he was so gay and didn’t like me,” she said to big laughs from her lifelong best friend who just so happens to now be engaged to Galvin. “We just always wanted to make something as a collective, and we’re so inspired by all these people that just made things with their friends and brought in a greater community. We brought in Owen, Patty and Jimmy and all these amazing people and wanted to create a sandbox where they could really own their roles and have agency and just get to have fun.”

It’s based on their short film and Lieberman said when they were pitching it around town, they said their vision was akin to 1993’s The War Room, a documentary about Bill Clinton’s 1992 presidential campaign. “They were like, what the hell? Insane. But we just wanted to do it in a more cinema verité way and make it our own in that way,” Lieberman said, adding that the other source of inspiration was Christopher Guest’s iconic mockumentaries like Best in Show, A Mighty Wind and Waiting for Guffman.

For this part, Tony Award-winning performer Platt singled out the biggest “treat and surprise” of the experience. It “was how incredible the young actors were at improvising and bringing themselves to the film and being in totally in their own skin, which is what theater camp’s all about. They really got the heart of the film and I’m so happy they came and sang for you guys because that was like the biggest treat in the world.”