The novella begins with Gregor Samsa waking up one morning to discover that he has been transformed into a giant insect. The story follows Gregor as he tries to cope with his new insect form and the challenges it presents. As a result of his transformation, Gregor becomes isolated from his family, who initially show concern but later grow increasingly distant and repulsed by his appearance.

Gregor's job as a traveling salesman becomes impossible to maintain, and he becomes a burden on his family. The narrative unfolds as Gregor struggles to adapt to his new existence and his family struggles to accept and understand his transformation. The relationship between Gregor and his family undergoes a significant transformation, reflecting the broader theme of alienation and the human condition.

"Metamorphosis" is often interpreted as a symbolic exploration of the human experience, touching on themes such as the dehumanizing effects of modern life, the breakdown of communication, and the inherent loneliness of existence. Kafka's unique writing style, characterized by its surreal and nightmarish quality, adds to the overall sense of absurdity and existential angst present in the novella.