King Hrothgar, the ruler of the Danes, is being tormented by a demon named Grendel. Every night, Grendel attacks King Hrothgar's wealthy mead-hall, Herot He kills Danish warriors, snatching them up as snacks. Hrothgar was a great warrior in his time, but now he's an old king and can't seem to protect his people. Fortunately, a young Geat warrior named Beowulf travels to Herot from his own lands overseas to help defeat beowulf.

Beowulf offers to fight Grendel himself. King Hrothgar gratefully accepts his offer. The next time Grendel attacks Herot, Beowulf is waiting for him. Choosing to fight Grendel in hand-to-hand combat, Beowulf wrestles the demon into submission and eventually tears off his arm at the shoulder. Grendel flees into the wilderness and dies. Beowulf, Hrothgar, and their followers throw a wild party to celebrate.

Unfortunately, Grendel has an overprotective mother who decides to avenge her son. Grendel’s mother attacks Herot but fled taking Hrothgar’s closest friend. Beowulf, his followers, and some of Hrothgar's Danish warriors track her to her lair in the lake. 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 kills her, even though her poisonous demon blood melts the blade. When Beowulf returns to the surface, carrying the sword hilt and Grendel's severed head, the Danish warriors have given him up for dead, but his own Geatish followers are still waiting patiently. When everyone sees that Beowulf has survived this second challenge, there is even more celebration.

Upon returning to Geatland, Beowulf becomes king because his uncle and cousin both die. Beowulf reigns as king for fifty years, protecting the Geats. But one day, Beowulf finally meets his match: a dragon, who was woken by a thief stealing his treasure. The dragon begins attacking the Geats so Beowulf takes a group of trusty warriors to the barrow for a final showdown with the monster. When they see the dragon, all but one of the warriors flees in terror. Only one man, Wiglaf, remains at Beowulf's side. With Wiglaf's help, Beowulf is able to defeat the dragon, but he is mortally wounded in the process.

After Beowulf's death, the Geats built a tower for him and inside were the treasures he had gathered over the years. The brave warriors rode around telling stories of their heroic leader.