Standard muscleman fantasy finds Siegfreid fighting evil personified in the guise of Morak. Morak is the son of the devil's messenger, Belial. Morak is attempting to take the throne of evil "on the day of the night in the day", or rather during an eclipse. To escape instant death by flames, before sitting on the throne, he must also wed Valkari. Siegfried who is invulnerable except to fire and gains temporary powers of invisibility (per "The Rings of Nibelung"), of course, battles Morak to save the beloved princess.