In 1880, two small meteors strike an island off the Pacific Coast and nobody pays much attention. Then the monsters start coming. Victims are found with a strange crest burned into them — one word: demiseed — and no one has an explanation. A young boy on the island is approached by two aliens: Zero, who introduces himself as the Space Sheriff, and a small companion who arrived in what is generously described as a miniature spaceship. Zero explains that an intergalactic criminal named Demi escaped custody and fled to Earth — specifically to this island — and is responsible for the meteors, the crest, and the monsters. Zero then possesses the boy's body, lends him his powers, and sends him to find and destroy Demi before things get worse than they already are.