Back in 1969, Jim Henson hadn’t yet started creating what would be known as the Muppets. Instead, he was pitching short films to NBC, including one called The Cube. Conceived as a part drama, part variety show, the Cube was “hosted” by a man named Richard Schaal who inhabited a white cube room that he could never leave. Other people, like guests, would wander in and out, but Schaal was stuck. Forever.

Believe it or not, the teleplay for this this aired on NBC’s Experiments in Television, back when TV was young.

The whole thing can be viewed here.