Beowulf, with fourteen companions, sails to Denmark, to offer his help to Hrothgar, king of the Danes, whose hall (called " Heorot ") has for twelve years been rendered uninhabitable by the ravages of a devouring monster (apparently in gigantic human shape) called Grendel, a dweller in the waste, who used nightly to force an entrance and slaughter some of the inmates.
In the vault he finds the corpse of Grendel; he cuts off the head, and brings it back in triumph.
This supposition is confirmed by evidence that seems to show that the Grendel legend was popularly current in this country.
The charter that mentions the Wiltshire " Grendel's mere " speaks also of a place called Beowan ham (" Beowa's home "), and another Wiltshire charter has a " Scyld's tree " among the landmarks enumerated.
In a vaulted chamber under the waves, he fights with Grendel's mother, and kills her.