The emissary of a race of disembodied energy creatures lands on 19th century Earth and enters the frame of a wild-west gunslinger. Attempting to reform its simple-mindedly vicious host, the symbiote induces him to become a semi-law abiding citizen. The pleasures of the flesh prove, however, to be the alien's undoing, and with its last gasp it imposes a galactic quarantine on earth. Just as silly as it sounds.