While The Thing is clearly Carpenter’s most influential work in this vein, it’s 1995’s In the Mouth of Madness that most completely renders the elements of cosmic horror on the silver screen. The rampage of cosmic terrors that come to reclaim our world, driving protagonist John Trent (played by a brilliant, anxiety-ridden Sam Neill) to the brink while warping reality into an apocalyptic hellscape, is straight out of Lovecraft (whose At the Mountains of Madness clearly inspired the title of Carpenter’s Madness). Even better, the film’s finale sees Trent realize Sutter Cane’s power has fully subsumed Trent’s own life and every event we’ve seen, making Madness the boldest exemplar of the genre’s reality-bending tendencies in film history. It’s a masterpiece — but one that doesn’t get the credit it deserves. It was far ahead of its time when the film premiered three decades ago, and it’s still at the forefront of cosmic horror film history.

To celebrate the film’s 30th anniversary, Inverse spoke to producer Sandy King Carpenter and members of the cast and crew to tell the story of In the Mouth of Madness. (Sam Neill and director John Carpenter declined to participate.)