Gregor Samsa, a traveling salesman, wakes up on morning to discover that he has transformed into a hideous creature. He finds himself to be some sort of vermin with multiple legs, and a hard shell. When his family calls for him to discover why he has slept so late (his work supports the family) he answers but his chirping voice is difficult for the others to understand. By the time his manager from the office arrives to check in on him, no one can understand him calling through the locked door.

He manages to unlock the door, and the family gets their first look at him. The manager is scared and flees the apartment. He returns to his room, where he hides under his couch. His sister begins to care for him, feeding him twice a day and cleaning the room while Gregor hides under the couch and covers himself with a sheet.

As things continue, Gregor learns to enjoy crawling around the walls so his sister clears the room to give him more crawling space. The family takes on tenants to help meet costs, and everyone begins to work. As his sister becomes more jaded through work she begins to care for Gregor less and less. One night while she plays violin for the tenants, Gregor leaves his room and gets closer. The music reminds him of his humanity, but when the tenants see him they become angry and give notice that they will leave.

The family becomes angry, and Gregor slowly returns to his room. He dies in the night and the family, relieved from the burden of his presence being gone, move to a new apartment to begin their lives again.