Beowulf is the longest and greatest surviving Anglo-Saxon poem. The setting of the epic is the sixth century in what is now known as Denmark and southwestern Sweden. The poem opens with a brief genealogy of the Scylding (Dane) royal dynasty, named after a mythic hero, Scyld Scefing, who reached the tribe's shores as a castaway babe on a ship loaded with treasure. Scyld's funeral is a memorable early ritual in the work, but focus soon shifts to the reign of his great-grandson, Hrothgar, whose successful rule is symbolized by a magnificent central mead-hall called Heorot. For 12 years, a huge man-like ogre named Grendel, a descendant of the biblical murderer Cain, has menaced the aging Hrothgar, raiding Heorot and killing the king's thanes (warriors). Grendel rules the mead-hall nightly.
Beowulf, a young warrior in Geatland (southwestern Sweden), comes to the Scyldings' aid, bringing with him 14 of his finest men. Hrothgar once sheltered Beowulf's father during a deadly feud, and the mighty Geat hopes to return the favor while enhancing his own reputation and gaining treasure for his king, Hygelac. At a feast before nightfall of the first day of the visit, an obnoxious, drunken Scylding named Unferth insults Beowulf and claims that the Geat visitor once embarrassingly lost a swimming contest to a boyhood acquaintance named Breca and is no match for Grendel. Beowulf responds with dignity while putting Unferth in his place. In fact, the two swimmers were separated by a storm on the fifth night of the contest, and Beowulf had slain nine sea monsters before finally returning to shore.
While the Danes retire to safer sleeping quarters, Beowulf and the Geats bed down in Heorot, fully aware that Grendel will visit them. He does. Angered by the joy of the men in the mead-hall, the ogre furiously bursts in on the Geats, killing one and then reaching for Beowulf. With the strength of 30 men in his hand-grip, Beowulf seizes the ogre's claw and does not let go. The ensuing battle nearly destroys the great hall, but Beowulf emerges victorious as he rips Grendel's claw from its shoulder socket, sending the mortally wounded beast fleeing to his mere (pool). The claw trophy hangs high under the roof of Heorot.
The Danes celebrate the next day with a huge feast featuring entertainment by Hrothgar's scop (pronounced "shop"), a professional bard who accompanies himself on a harp and sings or chants traditional lays such as an account of the Danes' victory at Finnsburh. This bard also improvises a song about Beowulf's victory. Hrothgar's wife, Queen Wealhtheow, proves to be a perfect hostess, offering Beowulf a gold collar and her gratitude. Filled with mead, wine, and great food, the entire party retires for what they expect to be the first peaceful night in years.
But Grendel's mother — not quite as powerful as her son but highly motivated — climbs to Heorot that night, retrieves her son's claw, and murderously abducts one of the Scyldings (Aeschere) while Beowulf sleeps elsewhere. The next morning, Hrothgar, Beowulf, and a retinue of Scyldings and Geats follow the mother's tracks into a dark, forbidding swamp and to the edge of her mere. The slaughtered Aeschere's head sits on a cliff by the lake, which hides the ogres' underground cave. Carrying a sword called Hrunting, a gift from the chastised Unferth, Beowulf dives into the mere to seek the mother.
Near the bottom of the lake, Grendel's mother attacks and hauls the Geat warrior to her dimly lit cave. Beowulf fights back once inside the dry cavern, but the gift sword, Hrunting, strong as it is, fails to penetrate the ogre's hide. The mother moves to kill Beowulf with her knife, but his armor, made by the legendary blacksmith Weland, protects him. Suddenly Beowulf spots a magical, giant sword and uses it to cut through the mother's spine at the neck, killing her. A blessed light unexplainably illuminates the cavern, disclosing Grendel's corpse and a great deal of treasure. Beowulf decapitates the corpse. The magic sword melts to its hilt. Beowulf returns to the lake's surface carrying the head and hilt but leaving the treasure.
After more celebration and gifts and a sermon by Hrothgar warning of the dangers of pride and the mutability of time, Beowulf and his men return to Geatland. There he serves his king well until Hygelac is killed in battle and his son dies in a feud. Beowulf is then named king and rules successfully for 50 years. Like Hrothgar, however, his peace is shattered in his declining years. Beowulf must battle one more demon.
A fiery dragon has become enraged because a lone fugitive has inadvertently discovered the dragon's treasure-trove and stolen a valuable cup. The dragon terrorizes the countryside at night, burning several homes, including Beowulf's. Led by the fugitive, Beowulf and eleven of his men seek out the dragon's barrow. Beowulf insists on taking on the dragon alone, but his own sword, Naegling, is no match for the monster. Seeing his king in trouble, one thane, Wiglaf, goes to his assistance. The others flee to the woods. Together, Wiglaf and Beowulf kill the dragon, but the mighty king is mortally wounded. Dying, Beowulf leaves his kingdom to Wiglaf and requests that his body be cremated in a funeral pyre and buried high on a seaside cliff where passing sailors might see the barrow. The dragon's treasure-hoard is buried with him. It is said that they lie there still.