For the past 30 years, a mysterious person known as Longmont Potion Castle has elevated prank calls to an artform. Whether it’s by dementedly mispronouncing words like “bruschetta,” terrorizing local businesses by asking if they have ridiculous nonexistent products, or successfully punking celebrities like Alex Trebek and Kiefer Sutherland, LPC’s deeply weird brand of absurdist comedy has garnered him a sizable cult following. Since 1988, when he was 16-years-old recording his prank calls on his parents’ answering machine, he’s been compiling his calls and releasing them on independent labels with the latest, Longmont Potion Castle 15, out last year.

Longmont Potion Castle’s off-kilter humor, bizarre vocal effects, and decades-long anonymity have built up his myth to the point where there’s now an imminent full-length documentary on the enigma. Where in the Hell is the Lavender House? The Longmont Potion Castle Story has been in the works since 2016 and on March 19, gets its world premiere. In anticipation of the release, Noisey’s premiering the official trailer. The clip tries to pin down what makes LPC so special and features “Executive Producer” Rainn Wilson describing his calls with, “it’s as if Salvador Dali got stoned and was living in suburban Denver.” Watch it below.

According to director Tom Rotenberg, the film features an interview with man behind Longmont Potion Castle, as well as sit-downs ranging from notable fans of LPC (including Wilson, Andrew Bujalski, Weyes Blood, Cattle Decapitation, Pissed Jeans, and more) his prank call victims, his collaborators, and even the mayor of Longmont, Colorado. Rotenberg told Noisey in an interview, “LPC has been so integral to kind of the lives of so many musicians and so many well known filmmakers. Making this film I was just struck by how dedicated his fans are.” He added, “This movie is his story too—to allow him to speak for himself and to talk about his process, what he does, and what it means to him.”