Professor Heinrik Ostertaag has invented a treatment that revives brain cells, but in order to test his theories, he must experiment on a human subject. Despite the protests of his best lab assistant Todd, he arranges for his other loose cannon assistant Roger to murder Arthur, an innocent man. He then performs the treatment on Arthur, reviving him from the dead. What Ostertaag does not realize is that, while dead, Arthur went to hell, and that by reviving him, the professor has allowed a demon to bridge the gap to our world. The demon possesses Arthur, turning him into a merciless beast who will stop at nothing to punish humanity. After Arthur escapes from the lab, Ostertaag, Todd and Rog must track him down and stop him before the authorities discover what they have done.