Written by David Gerrold and directed by Dennis Steinmetz, it first aired in the United States on September 7, 1974, on NBC.

When their raft washes ashore, they are met with a tyrannosaur they soon dub "Grumpy", who chases them till they reach a homely cave located up a steep cliff.

The next day, the Marshalls explore the jungle, where they discover a large, metallic "pylon" which emits a high-pitched whirring sound and observe three manlike simians attempting to create a fire while chanting an invocation in their native language.

The online review site Premium Hollywood described the episode in 2009 as "really a very boring start for the series", adding that it was likely toned down to avoid frightening its young viewership.

Erickson contrasts this with "standard operating procedure in the 1970s ... to lay all the cards on the table in the opening episode", and lauds the show's creators Sid and Marty Krofft for "having enough confidence in [their] young audience to unfold [the] series' exposition over a matter of weeks rather than minutes".