Grendel is a fearsome monster who lives underground in a cave with his mother. As spring begins, he encounters a ram and, irritated at the stupidity of the creature, tries to scare it away. The ram doesn’t move. Grendel talks angrily to himself and heads for the meadhall of Hrothgar, whose kingdom he habitually raids.
Grendel recalls his youth. Once, he got his foot stuck in between two tree trunks in the forest. A bull found him and charged at him, though unable to harm Grendel significantly. The bull charged again and again to no avail until, tired, it simply left. Then, a group of humans led by Hrothgar found Grendel, and were unsure what kind of creature he was. Grendel tried to talk to them, but they were frightened at his monstrous voice and attacked him. Grendel’s terrifying mother came and rescued him from the humans, who fled.
Grendel describes how the humans eventually developed agriculture and created settlements. As communities expanded, wars began to erupt and Hrothgar gradually gained power. The humans were relentless in their destruction of nature and of their human enemies. One night, once Hrothgar’s power was firmly established, an old blind man arrived at his meadhall and offered to sing for pay. This man, the Shaper, sang beautiful songs that glorified Hrothgar and his people. His songs enraged but also enchanted Grendel, who was swept away by their beauty. Once, when Grendel was spying on Hrothgar and the humans, the Shaper sang of two ancient brothers who feuded: one killed the other and so was cursed for eternity. According to the Shaper, Grendel is the descendant of the cursed brother. Greatly upset, Grendel rushed into the meadhall and tried to tell the Danes that he meant them no harm. But they were terrified at him and attacked him, so he fled.
After his encounter with the Shaper, Grendel visited the dragon, a wise but fearsome creature obsessed with his hoard of treasure. The dragon instructed Grendel about the humans, time, space, and the universe. Though Grendel had trouble following his abstract, philosophical ideas, he took away the main idea that all of life is meaningless when considered in the grand scheme of eternity. The dragon put a charm on Grendel, rendering him invulnerable to weapons. Shortly after, Grendel began his habitual raids on Hrothgar’s meadhall. On one raid, he encountered a particularly strong Dane named Unferth, who thought of himself as a noble hero. Grendel teased and toyed with Unferth, denying the existence of real heroes. Grendel let Unferth live, and so Unferth followed Grendel back to his lair in order to die nobly. Grendel refused to kill him, though, and brought him safely back to Hrothgar.
Grendel then remembers the arrival of Hrothgar’s queen, Wealtheow. Hrothgar was preparing for war with a rival king, but the king presented his sister Wealtheow as a gift in order to ensure peace between the two kingdoms. Grendel was fascinated by Wealtheow’s grace and beauty and tormented by her just as he once was by the Shaper’s art.
After Hrothgar’s brother dies, his nephew Hrothulf comes to Hart. Hrothulf is highly critical of Hrothgar’s rule. He and his adviser, an old man named Red Horse, theorize about the justice or injustice of revolution. Hrothulf takes no action, though, and continues to live under the care of Hrothgar, while still plotting to eventually overthrow Hrothgar. One night, Grendel decides to “impute” a dream to Hrothgar involving two trees that have grown so that they wind around each other. Another night, while spying on the Danes, Grendel sits down in a religious area with icons of the Danes’ gods. An old priest named Ork comes to the area, but cannot see Grendel. Grendel speaks to him and pretends to be his god, toying with the human and his religious beliefs.
Grendel becomes bored with his continued raids. The Shaper dies and Grendel goes to watch his funeral. A group of strangers arrive at Hrothgar’s kingdom, calling themselves the Geats. The unnamed leader of their group, who can be identified as the hero Beowulf, frightens and excites Grendel. Beowulf tells Hrothgar and his men that he has come to defeat Grendel for them. At Hrothgar’s meadhall, he impresses the Danes with stories of his heroic accomplishments.
After all the humans fall asleep, Grendel breaks into the meadhall, looking for Beowulf. He grabs a sleeping man to eat him, but it turns out to be Beowulf, who was only pretending to sleep. Beowulf grabs Grendel and begins to overpower him. He forces his extreme ideas—in particular, the idea that Grendel’s mind makes the world what it is—upon Grendel, who finds Beowulf’s words as painful as his unrelenting grasp on Grendel’s arm. Beowulf tears off Grendel’s arm and Grendel flees, defiantly shouting that Beowulf’s victory was mere chance and meaningless. Grendel dies in the forest, surrounded by animals.