A Roman centurion who had died in battle is resurrected from the dead by Zeus. The centurion is ordered by Zeus to save his daughter Athena from a Demon God called Neff in the Underworld. To become able to withstand the perils, the warrior gets the ability to collect three spirit balls on each level, the last of which transforms him into a human/beast hybrid of formidable power.
After a series of battles in a journey that ends in Dis, the centurion finally defeats Neff and rescues Athena. In the original arcade game, the end credits are interspersed with images of actors in costumes for the different characters and monsters of the game, implying the whole game was a film production.