Beowulf is set in a post-industrial castle that defends the border of an unnamed kingdom. It is terrorized by a demon named Grendel, who kills the castle’s defenders, one by one.
After fighting his way past several soldiers trying to keep anyone from entering or leaving, the warrior Beowulf offers his help to the castle’s king, Hrothgar, who welcomes his help.
Hrothgar has a daughter named Kyra, who is loved by Roland, the castle’s strongest soldier, but she does not return his affections.
It is revealed that Hrothgar’s wife (and Kyra’s mother) committed suicide when she found out Hrothgar had an affair.
The woman he had an affair with was actually an ancient being who had originally lived on the castle’s lands.
The affair resulted in an offspring, Grendel.
Beowulf and Grendel fight, wounding each other.
Later, after recovering, they fight again and this time Beowulf rips Grendel’s arm off with a retracting cestus.
That night the castle celebrates as they believe Grendel is dead.