A film adaptation of the classic sword and sorcery hero, Conan the Barbarian. A horde of rampaging warriors massacre the parents of young Conan and enslave the young child for years on The Wheel of Pain. As the sole survivor of the childhood massacre, Conan is released from slavery and taught the ancient arts of fighting. Transforming himself into a killing machine, Conan travels into the wilderness to seek vengeance on Thulsa Doom, the man responsible for killing his family. In the wilderness, Conan takes up with the thieves Valeria and Subotai. The group comes upon King Osric, who wants the trio of warriors to help rescue his daughter who has joined Doom in the hills.

People are dying mysteriously and gruesomely, and nobody has a clue what the cause is. Only health worker Mike Brady has a possible solution, but his theory of killer slugs is laughed at by the authorities. Only when the body count begins to rise and a slug expert from England begins snooping around does it begin to look like Mike had the right idea after all.