King Hrothgar, the ruler of the Danes, is troubled by the rampages of a demon named Grendel. Every night, Grendel attacks King Hrothgar's wealthy mead-hall, Heorot, killing Danish warriors and sometimes even eating them.
Fortunately, a young Geat warrior named Beowulf travels to Heorot Hall from his own lands overseas to lend a helping hand—literally.
Choosing to fight Grendel in hand-to-hand combat, Beowulf wrestles the demon into submission and eventually tears off his arm at the shoulder. Mortally wounded, Grendel flees into the wilderness and dies.
Beowulf dives into the lake and finds the cave, where he takes on Grendel's mother in another one-on-one battle. Seizing a nearby sword from Grendel's mother's stash of treasure, he slays her, even though her poisonous demon blood melts the blade.
Beowulf, Hrothgar, and their followers throw a wild party to celebrate. Hrothgar also gives Beowulf many presents and treasures to reward him for his heroic defeat of the demon.
Beowulf says goodbye to King Hrothgar and sails back to Geatland, where he is a lord in the court of King Hygelac. Eventually, Hygelac and all his relatives are killed in different blood-feuds,