Set in 507, Beowulf is a legendary Geatish warrior who travels to Denmark with his band of soldiers, including his best friend, Wiglaf. They meet King Hrothgar, who needs a hero to slay Grendel, a hideously malformed troll-like creature with appalling strength and cunning. Grendel attacks Heorot, Hrothgar’s mead hall, whenever the Danes held a celebration, and Hrothgar has been forced to close the hall. Upon arriving, Beowulf becomes attracted to Hrothgar’s wife, Queen Wealtheow, who reciprocates his interest.
Beowulf and his men celebrate in Heorot to lure Grendel out. When the beast attacks, Beowulf engages him unarmed and naked. During the fight, Beowulf discovers that Grendel has hypersensitive hearing, which is why he interrupts Hrothgar’s celebrations – the noise they make is physically painful to him. After his left eardrum is ruptured by Beowulf, Grendel shrinks in size and attempts to escape. Beowulf restrains Grendel and severs his left arm with the door. In thanks for freeing his kingdom from the monster, Hrothgar gives Beowulf his golden drinking horn, which commemorates Hrothgar’s victory over the mighty dragon Fafnir.
In his cave, the dying Grendel tells his mother what was done to him, and she swears revenge. She travels to Heorot and slaughters Beowulf’s men while they are sleeping. Hrothgar tells both Beowulf and Wiglaf, who had been sleeping outside the hall during the attack, that it was the work of Grendel’s mother. She is the last of the Water Demons, who were thought to have left the land. Beowulf and Wiglaf travel to the demon’s cave to slay her. Beowulf enters the cave alone and encounters the demon, who takes the form of a beautiful woman. She offers to make him the greatest king who ever lived, in exchange for Hrothogar’s drinking horn and a son, to replace Grendel.