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.
There are similar alternative possibilities with regard to the explanation of the striking resemblances which certain incidents of the adventures with Grendel and the dragon bear to incidents in the narratives of Saxo and the Icelandic sagas.
The water-demon Grendel and the dragon (probably), by whom Beowulf is mortally wounded, have been supposed to represent the powers of autumn and darkness, the floods which at certain seasons overflow the low-lying countries on the coast of the North Sea and sweep away all human habitations; Beowulf is the hero of spring and light who, after overcoming the spirit of the raging waters, finally succumbs to the dragon of approaching winter.
When all but Beowulf are asleep, Grendel enters, the iron-barred doors having yielded in a moment to his hand.
Grendel, though mortally wounded, breaks from the conqueror's grasp, and escapes from the hall.
In the vault he finds the corpse of Grendel; he cuts off the head, and brings it back in triumph.
Yet even before his encounter with Grendel, he had won renown by his swimming contest with another youth named Breca, when after battling for seven days and nights with the waves, and slaying many sea-monsters, he came to land in the country of the Finns.
On the other hand, it would be absurd to imagine that the combats with Grendel and his mother and with the fiery dragon can be exaggerated representations of actual occurrences.
It is a reasonable conjecture that the tales of victories over Grendel and the fiery dragon belong properly to the myth of Beaw.
There is, as we shall see afterwards, some ground for believing that there were circulated in England two rival poetic versions of the story of the encounters with supernatural beings: the one referring them to Beowulf the Dane, while the other (represented by the existing poem) attached them to the legend of the son of Ecgtheow, but ingeniously contrived to do some justice to the alternative tradition by laying the scene of the Grendel incident at the court of a Scylding king.
This supposition is confirmed by evidence that seems to show that the Grendel legend was popularly current in this country.
The Christian passages, which are poetically of no value, are evidently of literary origin, and may be of any date down to that of the extant MS. The curious passage which says that the subjects of Hrothgar sought deliverance from Grendel in prayer at the temple of the Devil, " because they knew not the true God," must surely have been substituted for a passage referring sympathetically to the worship of the ancient gods.