The discovery of an Earth-like atmosphere on the 13th moon of Jupiter leads to the sending of a crew of five male astronauts, armed with handguns, to investigate.

Prasus hopes the spacemen will stay and help him destroy the monster, which is a slender, male hominid creature, around six feet tall with dark, pitted skin, impervious to bullets, and described as a "man with the head of a beast".

[3] In a contemporary reviews, The Monthly Film Bulletin stated: "Even the most dedicated connoisseurs of the artless are likely to find this British attempt at science-fiction something of a strain on their patience.

The picture, staged on a very modest, not to say meagre, scale, is, despite the presence of the monster, more of a folk dance display than an outer space thriller.

Anthony Dexter, imported from America, Susan Shaw, Harry Fowler, Paul Carpenter, Sydney Tafler and other well-known players do their best to pep up the fantastic script, but retire defeated.