The main character of the story, Gregor, wakes up late for work one morning to discover he is no longer human. Instead, he is an insect-like creature, and he lives the rest of his life reflecting on his former existence as a traveling salesman, trying to avoid his overbearing father, and crawling the walls of his bedroom, where he eventually dies in a state of "empty and peaceful rumination."
As Gregor's 17-year-old sister, Grete treats her brother with kindness and compassion when she realizes he is a bug. She feeds him and attempts to figure out his needs, but she later comes to resent his inability to work and provide for their family. Grete does not know that while working as a salesman, Gregor was saving up to pay for her violin lessons.
Retired from a failed business, Mr. Samsa rarely leaves the flat and relies on his son to provide for the family. He has no patience for his son's predicament, losing his temper and injuring Gregor in fits of rage. When forced to return to work, however, Mr. Samsa's vigor seems to return, and he feels a sense of relief once Gregor dies and his family can move on.
Gregor's frail and aging mother, Mrs. Samsa loves her son but grows hysterical each time she catches a glimpse of his hideous appearance. Her daughter and husband try to persuade her to stay out of his bedroom. One day she enters his room to help Grete rearrange furniture and faints at the sight of him clinging to a wall, causing Mr. Samsa to retaliate against Gregor in a fit of rage. Even Mrs. Samsa, however, pitches in to earn money by sewing.