The novel begins in the twelfth year of Grendel’s war with the humans. Wandering outside, he encounters a ram and tries to scare it away. He throws a rock at it, strikes the ground, and howls, but the ram doesn’t move. Grendel is frustrated by the ram’s mindless sexuality and “ache to mount whatever happens near” with the onset of spring.
The ram’s lack of reaction to Grendel symbolizes the mindless indifference of nature, which irritates the lonely Grendel. Grendel’s anger at the ram shows the monster to be different from other wild creatures.
Grendel walks away from the ram, toward a forest, reflecting on his difference from animals and asking the sky why creatures like the ram are so undignified. He raises his middle finger at the unresponsive sky. While different from creatures like the ram, Grendel reflects that he is not noble and calls himself a “pointless, ridiculous monster” who murders men, children and cows, something of which he is neither proud nor ashamed. As Grendel observes the beginnings of spring in nature all around him, he remembers killing humans at this very location. He cries out angrily and smashes some trees.
Grendel’s speaking to the sky shows how isolated and desperate for someone to talk to he is. But he gets no response from the natural world, which is unsympathetic to his feelings. Grendel’s thoughts shed light on his identity as a monster: while he is different from wild animals and able to look down on them as undignified, he still does not consider himself to be a noble creature.
A doe in a clearing sees Grendel and runs away. Grendel cries out that this is unfair, since he has never killed a deer (since cows have more meat). Grendel notes that deer and other animals “see all life without observing it.” He walks along, muttering and talking to his only companion: his shadow. He describes his words as walls between himself and the rest of the world.
The deer underscores for Grendel how unfair the unthinking natural world is. Animals like the deer go through life without examining it, in contrast to the theorizing and thinking that characterizes Grendel, the humans, and the dragon. Talking to his shadow, Grendel describes his use of language as something that separates himself from the rest of nature like a wall.
The beginning of spring is apparent even in the underground lair where Grendel lives with his foul, monstrous mother. He has felt the stirrings of spring and so has come out of his den, swimming through a marshy lake filled with firesnakes, to satisfy his hunger for blood. Enjoying being out under the open night sky, Grendel walks to some nearby cliffs.
Grendel describes his mother without any affection, showing that his only familial relationship is a loveless one that does not assuage his loneliness.
Grendel shouts and mocks the cliffs, from whose height he could fall and die. He is momentarily frightened by the sound of his own voice. Leaving the cliffs, he makes his way for the meadhall of Hrothgar, king of the Danes, and continues to talk to nature. Wolves and other animals are alarmed when they see Grendel coming.
Far from finding a sympathetic friend in nature, Grendel can’t even find an antagonist: his attempt to mock and provoke the cliffs elicits no response. Even wolves flee from Grendel, leaving him entirely alone—except, that is, for the humans in whom he finds a rival.
Grendel thinks of his mother sleeping in their underground lair. He thinks that she feels guilty for an ancient crime and that she must have some human ancestry. But according to Grendel, his mother does not think or ponder about her life at all. When they sleep, she grabs at him to pull him near but he breaks away. Grendel remembers that he used to ask her why they lived in their underground den but she would never respond. But this was before Grendel met the old dragon, who Grendel says told him the truth.
Grendel’s mention of human ancestry hints that he and the humans might not be drastically different, but actually related. Despite his mother’s attempts to be literally close to Grendel, he feels distant from her. His constant questioning and his use of language separate him from his mother.
Grendel comes to Hrothgar’s meadhall, where he’s been busting down the door and terrorizing the inhabitants for eleven years now. Each time, people cry out and an old blind man with a harp, called the Shaper, flees out a back window. Hrothgar’s men try to fight Grendel but never succeed. This time, they try blowing out all the candles and hiding, but Grendel can see clearly in the dark. He kills and eats his fill of men, as he usually does.
Grendel takes pleasure in rampaging and murdering the humans. He derives a satisfaction from his interactions with the Danes that he cannot get from interactions with any other creature.
As he leaves the meadhall, Grendel hears various humans saying that he is a punishment sent to them because a god is angry and Hrothgar’s people are sinful. He leaves the meadhall, as the humans are praying to their gods, which Grendel refers to as merely “sticks and stones.” Grendel notes that the king does not pray, because he has his own theories. He recalls the dragon saying of the humans, “They’d map out roads through hell with their crackpot theories!”
Watching from the edge of the forest, Grendel observes as the humans pray and then prepare a funeral mound for the deceased—or at least what Grendel has left behind of their bodies. Builders replace the door to the meadhall, adding improvements to try (in vain) to keep Grendel out. The humans burn the remains of the dead on a funeral pyre and throw golden rings, swords, and helmets onto the fire. They sing a funeral song, which makes Grendel angry. Frustrated and blinded by the rising sun, Grendel goes back to his underground home.
The Danes’ religious rites are a further example of humans’ theories. Grendel scoffs at the practice, but also feels excluded by the funeral song, which emphasizes the human community as distinct from him as a monster.