This film is a sci-fi update of the famous Medievil English poem written by an anonymous author.
In a castle somewhere in the future or the past, Evil itself has spread. The army has put up a ring of quarantine around the place, and nobody is allowed to leave the place alive.
A strange man, Beowulf (Christopher Lambert), arrives one day and offers his help. Since any man is helpful, he is allowed to hunt the threat, which comes at night in a shapeless blur with the sole intent to kill.
However Beowulf also seems to have a dark secret: His fatal wounds heal quicker than small ones of others, and he is the first one ever to wound the beast. So, courage is building up in the rows of the few that might live to see another day.