In the late 1970s, science fiction and cinema changed forever. Star Wars helped usher in the era of the outer-space blockbuster, while Ridley Scott’s Alien crystallized a sinister vision with some of the most horrific creature design ever seen. But as the new documentary Jodorowsky’s Dune argues, neither may have become the classics we know today were it not for another epic film — one that nobody has ever seen.

Alejandro Jodorowsky is the avant-garde filmmaker behind cult classics like El Topo and The Holy Mountain, and in 1975 he began work on a surrealistic adaptation of Frank Herbert’s Dune. His vision was trippy and fantastic — "I did not want LSD to be taken, I wanted to fabricate the drug’s effects," Jodorowsky says. To bring it to life, he assembled a legendary creative team, including artists Jean “Moebius” Giraud and H.R. Giger, with future Alien writer Dan O’Bannon handling visual effects. Jodorowsky convinced everyone from Salvador Dalí to Orson Welles to star in his epic. Then the filmmaker assembled a series of books containing every storyboard, ship design, and piece of art — and sent them off to the major studios to help get funding.

Nobody took the risk, but with a riveting mix of interviews and gorgeous animated storyboards, Jodorowsky’s Dune makes the case that the film changed the world anyway — its influence popping up in everything from Star Wars to Raiders of the Lost Ark. Part celebration, part cinematic whodunnit, it’s one of the most engrossing films in recent memory, and we spoke with director Frank Pavich about bringing the unique tale to life.