I’m sure we’re all familiar with Dark Crystal, so we know that Jim Henson can be weird and tackle slightly more mature subject matter. But there is little in his oeuvre that is quite as mind-bending as the Muppetless The Cube. This 1969 teleplay was produced for an NBC anthology series called Experiment in Television, which featured, appropriately enough, various experimental films, plays, and documentaries. One episode even featured Marshall McLuhan explaining his oft-cited theory that “the medium is the message.”

Even among all these oddities, however, Jim Henson’s The Cube stands out. It’s a 53-minute bottle film — taking place almost entirely in a single room. A man awakes in a white cube, unsure of where he is or how he got there. There are no windows, no door. Just walls of white panels.

It doesn’t take long for someone to open a section of the wall and bring in a stool for our nameless man in the cube. But when he closes the “door” behind him, our protagonist can’t open it back up. And thus begins the parade of people, dozens of them, taking turns going in and out of various invisible doors in the titular cube.

The interactions start off strangely enough — why is there strawberry jam on the stool? Who is this woman who claims to be the protagonist’s wife even though he doesn’t recognize her? But they quickly escalate, calling into question the nature of reality, our protagonist’s sanity, and raising questions about what the cube is exactly. Jim Henson himself even makes an uncredited cameo as the voice of a gorilla in a tutu.

As people come and go, delivering supplies to the man, harassing him, or even attempting to seduce him, the room changes around him inexplicably. Beds, couches, fully stocked liquor cabinets, and other furniture mysteriously appear. A full band slips in and sings a song with the line “you’ll never get out ‘til you’re dead,” before it’s revealed to be a recording as the record skips repeatedly on the word “dead.”

The Cube offers many questions but no answers. Is the man living in a simulation? Is he on TV? Are the people around him actors? Is any of it real at all? Does matter exist?

Even in a post-Twilight Zone world, The Cube feels uniquely bizarre, more akin to the modern dystopian anthology series Black Mirror than anything else. While it’s not true lost media, it remains relatively obscure. It only aired twice, there’s a sold-out DVD listing on Amazon, and it only occasionally makes an appearance on streaming services in any official capacity.

Your best bets right now are a pair of YouTube uploads, both embedded above. One is a much higher-quality transfer of a black-and-white kinescope film with remastered audio. Unfortunately, it also cuts out most of the song due to copyright. The other upload is full color and retains the song, but is a generally lower quality rip with muddier image and audio. Regardless of which one you choose, it’s a wild and thoroughly enjoyable ride that shows just how twisted the mind of Jim Henson could be.