Beowulf asks Hrothgar again to support his men if Beowulf himself dies in combat with Grendel’s mother. He also wants the king to send his treasures to Hygelac in Geatland and show everyone back home how generous Hrothgar was to him. Beowulf wants his sword given to Unferth, as he will take Hrunting with him to battle, even if he dies with it. After this quick speech, Beowulf dives into the cursed lake, and it takes him most of the day to reach the bottom. Grendel’s mother can tell right away that a human has entered her lair. She grabs the hero, but he is protected by his armor and mail. As Grendel’s mother drags Beowulf “to her court,” various sea creatures attack him before he can wield his weapons. In the villain’s lair, Beowulf tries to strike her with Hrunting but finds it useless; however, remembering his heroic reputation and legacy, Beowulf remains confident. 

Beowulf throws Hrunting aside and assumes he will have to rely on his physical strength, as he did in the fight with Grendel. Though he pushes her to the ground once, Beowulf is also impressed, even “daunted” by the strength of the monster. Beowulf begins to think he may lose this battle, leaving the outcome up to God. Then, however, he spots a sword on the wall of Grendel’s mother’s lair, a weapon from the age of the giants. The weapon is so imposing and heavy that only Beowulf can manage to remove it from the wall and wield it. He strikes Grendel’s mother in the neck, decapitating the beast. At the death of the monster, light shines in the cave, symbolizing that good has defeated evil. Beowulf sees Grendel’s body and becomes infuriated, wanting to avenge all those he and his mother desecrated. He cuts off Grendel’s head in a fury. 

Meanwhile, Hrothgar and his men wait by the lake, assuming the hero has been killed. Once the king and his own men have given up hope and gone back home, Beowulf’s Geats remain, keeping the faith. Through the power of God, the atmosphere around Beowulf transforms and hoards of treasure are revealed to him. He does not take the spoils, except for Grendel’s head and the handle of the sword he used to slay the beast. Beowulf has rid the tarn of the treacherous creature, making it safe for people to travel in the future. The hero emerges to the praise and relief of his thanes; four men have to struggle to carry Grendel’s head to Heorot. 

When he returns to the hall with the head of the monster, Beowulf stuns Hrothgar and his people. He offers the head to Hrothgar as a trophy representing their victory over Grendel and his mother. Beowulf admits that the battle was difficult and that he needed the help of God and a magical sword to defeat the beast. He declares triumph over the monsters and revenge for the Danes, guaranteeing that they no longer need to live in fear. Beowulf gives the sword’s hilt to the king. As Hrothgar admires the hilt while recalling the history of the biblical flood engraved on it. He distinguishes Beowulf and praises his bravery and dedication before reestablishing the former promises made between the two. Hrothgar contrasts Beowulf to Heremod, a king whose “rise in the world brought little joy / to the Danish people.” Despite God’s blessing, Heremod was a traitor of his people and suffered greatly; this is meant as a lesson to Beowulf that he should maintain his “true values” and not stray from them or he will suffer consequences like those of Heremod.

Hrothgar continues to speak, musing on the ways that power can be abused by kings. When kings acquire great influence, they can become careless, feeling invincible and endlessly blessed. He exercises power over his people, but he may begin to take his position for granted. Hrothgar warns that kings who become complacent place themselves in danger; he may “ignore the shape of things to come.” Eventually, all kings die and their material goods pass to the next heir. Hrothgar advises against becoming too attached to treasures at the cost of one’s “eternal rewards” in the afterlife. In his many years as king, Hrothgar has seen enough to confirm all of these insights. Even he fell victim to a sort of complacency in not expecting the reign of terror that would be visited upon the Danes in the form of Grendel. The king is grateful to have seen the end of the monster, and he will reward Beowulf with many handsome treasures. A feast begins when Hrothgar concludes his speech. 

Eventually, the king retires to bed, and an exhausted Beowulf also seeks rest. The next morning, the Geats awaken ready to travel home, but before they leave, the hero orders that his sword Hrunting be delivered to Unferth, not begrudging the sword for failing him in the conflict with Grendel’s mother. Once the men are gathered and prepared to depart, Beowulf formally addresses Hrothgar to announce that they want to return to Hygelac in Geatland. The hero thanks the Danes for their hospitality and vows to repay the favors when called upon. He also assures Hrothgar that his king, Hygelac, will agree with Beowulf’s promises and follow through when necessary. Beowulf tells Hrothgar that he would welcome his eldest son, Hrethric, to Geatland in the future. Hrothgar approves Beowulf’s speech and praises his heroic qualities; he even asserts that Beowulf should be king some day because of his impressive leadership. The king credits Beowulf with uniting the Danes and Geats despite prior conflicts between the two peoples. Treasures are loaded onto Beowulf’s ship, and when they say goodbye, the king becomes emotional because he feels he will never see the hero again. Hrothgar would continue to be a respected and valiant king for the rest of his reign.

The Geats embark on the voyage home and are cheered to see the coast of their homeland as they approach it. Beowulf comes ashore and goes to see his king, Hygelac, while the treasures are unloaded from the ship. The poet describes Queen Hygd, a young “thoughtful” woman by contrasting her to Queen Modthryth, who was cruel and vicious. The latter reformed, though, after marrying Offa, who would become a “hero king.” Word reaches Hygelac that the hero has returned, and he welcomes Beowulf warmly before asking him questions about the journey and the battles. He thanks God that Beowulf and the others have returned, admitting that he was afraid for their safety. Beowulf proudly recounts his victory over Grendel before returning to the first night in Denmark. He describe the feast and reports on the upcoming mar in marriage of Hrothgar’s daughter, Freawaru, to Ingeld, a match that is meant to “heal old wounds and grievous feuds,” but which Beowulf fears may not be enough to settle old feelings of revenge in the hearts of Ingeld’s Heathobards.