Max is a lonely 9-year-old boy grappling with the complexities of his life, including his divorced parents and an older sister, Claire, who fails to intervene when her friends destroy Max's snow fort during a snowball fight. Frustrated and feeling neglected, Max acts out by vandalizing Claire’s room and ruining a frame he had crafted for her. The situation worsens when his mother, Connie, invites her boyfriend, Adrian, to dinner, leading Max to feel further isolated on a night when they were supposed to spend time together. Dressed in his wolf suit, Max unleashes his fury on the household, culminating in a moment of anger where he bites Connie's shoulder. Scolded and scared, he runs away from home, eventually discovering a small boat at the edge of a pond.
This boat takes him to an enchanting island inhabited by a group of seven large monsters known as the Wild Things—those being Carol, Ira, Judith, Alexander, Douglas, the Bull, and KW. Upon his arrival, Max witnesses Carol in the throes of a tantrum triggered by KW's departure. Despite initially struggling to fit in and facing the growing suspicion of the Wild Things, Max cleverly convinces them that he is a king with magical abilities who can instill peace among them. Impressed by Max’s boldness, they crown him king, and he leads them in a “wild rumpus,” a chaotic but joyous celebration where the Wild Things romp about and tackle each other, ultimately collapsing in a heap with Max nestled in the center.
During his time on the island, Carol shows Max a model he made, illustrating how he envisions the island should look. Inspired by this vision, Max orders the construction of a grand fort. However, tensions arise when KW brings her owl friends to visit; Carol perceives them as intruders, leading to discord among the group. As frustrations come to a head during a dirt clod fight, Max tries to maintain peace, but the situation escalates when Alexander gets hurt, angering Carol.
Max finds himself torn as he overhears a secret from Alexander—that he is not truly a king and that Carol must never discover his truth. When Carol’s mood plummets during the night, he allows his rage to take over and, in a fit of anger, tears off Douglas's arm, revealing only sand within. This frightening outburst leads to Max fleeing deeper into the woods, where he is ultimately saved by KW, who kindly hides him away. After this encounter, KW reveals the burden of their lives with Carol's tantrums, making Max reflect on his own actions and the struggles his mother faces.
As Max begins to understand the weight of these experiences, he departs from the island, leaving behind a thoughtful token for Carol. When he encounters Carol, he declares he is returning home because he does not wish to be a king anymore. The Wild Things, now aware of Max's decision, escort him back to his boat. As he prepares to leave, Carol rushes to him after finding the token. In a poignant farewell, they howl together, forging a connection despite the impending goodbye, joined by the others in their chorus.
Upon returning home, Max is warmly welcomed by his mother, who offers him comfort in the form of soup, a slice of chocolate cake, and a glass of milk. As they sit together, Max watches her fall asleep at the table, finding peace in their renewed bond and the love that remains despite the chaos of his imagination.
