The following summary will give an overview of the story up to the point where Benjamin Bagby's re-telling of Beowulf stops, encompassing roughly the first third of the entire epic (lines 1-1062):
Following the formal call of ‘Hwaet!’ (Listen!), the scop reminds the listeners of some geneology: the legendary arrival of the great leader Scyld, found in a boat along the Danish coast, a solitary baby with no possessions. He grows up to become a unifier, war-leader and king of the Danes. On his death he is again set adrift, but now the funeral boat is piled high with treasure and the standard floats in the wind on the mast above him. He leaves a son, Beow, already famous as a king in South Sweden (the northern part of Denmark in the fifth century). Beow carries on the Scylding line as a good and able ruler and is succeeded by his son Halfdane. Halfdane in turn is a worthy king, and has three sons – Heregar, Hrothgar and Helga – and a daughter, Yrsa, who marries Onela of the royal line of Sweden. Eventually, Hrothgar becomes king and rules long and well.
With the kingdom stable, Hrothgar orders that a great banquet hall be built. Workmen from far and near are brought to build and decorate this royal building. Its fine workmanship and gilded gables are famous in Denmark and abroad. Hrothgar names the hall ‘Heorot’ (Hart). The drinking and laughter of the warriors, and the harping and songs of the scop provoke a savage monster named Grendel, a descendant of Cain, who lives in the marshes nearby cannot bear this human gaiety in his loneliness. Only later do we learn details of the creature: that it takes four men to carry his head on a spear, and that his hand has sharp claws like steel spikes. For weeks and months Grendel visits the hall nightly, devouring sleeping warriors and carrying off others to the moor to feed on later. At last, only drunken, boasting fools will linger in the hall after dark, until they too are slaughtered.
Twelve years pass, and in the form of sad songs the news of Hrothgar's dilemma travels eventually to other lands. Beowulf, sister's son to Higelac, King of the Geats, hears of Hrothgar's distress, and with consent from his uncle, sails with fifteen companions from southwestern Sweden on the east coast of the Oslofjörd. When the Danish coastal watchman learns that they have come to Hrothgar's aid, he shows them the path to Heorot. The Geatish warriors march with their spears, swords, helmets, shields and chain-mail to the high-gabled hall. At Heorot Beowulf and his men enter with challenges and formal speeches, the strict codes of a warrior’s behaviour in court. King Hrothgar had earlier given protection to Beowulf's father, Ecgtheow, during a feud. Learning Beowulf's name, Hrothgar recalls hearing of the extraordinary strength and reputation of the Geatish hero: he has the strength of 30 men in his hand-grip.
The strangers are warmly received and Beowulf is seated on the bench with Hrothgar's young sons. No Dane has confronted Grendel and lived. But the enthusiastic welcome shown to the Geats irritates the jealous Unferth, a drunken courtier sitting at Hrothgar's feet, who taunts Beowulf for having been defeated in a legendary swimming contest with Breca. Beowulf sets the record straight by recounting the dangers – attacking sea-monsters, storms, vast distances – and claiming that they had merely dared each other to a boyish hunt for sea-beasts. Separated by the winter storm, they swam, carrying swords and wearing chain-mail, two different paths: Breca to Norway and Beowulf to the land of Finns. Beowulf ends his retort with a taunt that Unferth has slain his own brother, the ultimate crime, even though by accident. With such ‘heroes’ as this, it's no wonder the Danes can't deal with Grendel themselves! The queen, Wealhtheow, pours ritual mead for the feasting warriors and Beowulf boasts to her that he will defeat Grendel or die in the attempt.
At nightfall Hrothgar and all the Danes depart from Heorot to sleep elsewhere, leaving Beowulf and his men to occupy the hall benches. Beowulf removes his helmet, chain-mail and weapons and boasts again to use no weapon in this fight, since Grendel uses none. As darkness descends Grendel comes gliding up from the misty marshes, and pushes open the great door, his eyes gleaming with an evil light. Immediately he grabs and eats a sleeping warrior. Next, the monster reaches for Beowulf, but the hero grasps his arm in return and rises to his feet. Beowulf’s men cannot help him since Grendel has put a spell on all weapons so that none can harm him. During the ferocious stuggle that follows, the hero wrenches off Grendel's arm. The sounds of the combat terrify the Danes outside: Grendel howling with pain, benches torn up and overturned, the hall shaken to its foundations. Grendel, leaving a trail of blood, escapes without his arm and limps back to the fens where he dies. Beowulf fixes the arm high above the hall as a symbol of victory. Heorot is cleansed of the evil monster, and in the morning people come from far and near to inspect the sight, following Grendel's trail to a boiling pool of bloody dark water in the marshes.
Young and old race their horses jubilantly back from the water, praising Beowulf, while an old bard, keeper of many ancient stories, makes up a new song about Beowulf’s deeds of the previous hours. He also sings the well-known story about Sigmund and the dragon. As the morning fog clears and the Danes converge on Heorot, Hrothgar appears with his queen and her retinue of maidens. Seeing the wrecked hall and Grendel’s arm, he gives thanks, praising Beowulf, offering to take him as a son, and promising him rich rewards. Beowulf gives a speech in reply: he describes the combat and regrets only that he cannot show Grendel’s entire body. Everyone agrees, looking at Grendel’s claw, that no sword could have ever defeated the monster. Order is quickly made in the half-wrecked hall, and a great celebratory feast is prepared: mead is poured and Hrothgar makes good on his promise: Beowulf is given a golden standard, a richly adorned helmet and chain mail, a priceless sword, and eight horses, one with a royal saddle decorated with jewels. Beowulf’s men are also given gifts, and the Geatish warrior killed by Grendel is atoned with gold.
The bard ends the story by reminding us that in those days God controlled all mankind, as He still does today. Still, human prudence in all things is best. Anyone who lives for long in this world will endure much: both good and evil.