An artist, John Jaspers (Mark Frost), sells his soul to the mysterious M (as for Mephistopheles) (Andrew Divoff) in order to avenge the death of his girlfriend, Blue (Jennifer Rope), at the hands of a gangster. However, the deal has an unexpected price, and he is periodically transformed into a horned demon with a passion for killing and becomes M's assassin. After meeting psychologist Jade De Camp, he rediscovers love and turns against M and his psychotic lover, Claire. He discovers that M plans to release a giant monster called the Homunculus, thereby opening the gates of Hell, and sets out to stop him.