The nameless narrator (Edward Norton) is a traveling automobile company employee who suffers from insomnia. His doctor refuses to give him medication and advises him to visit a support group to witness more severe suffering. The narrator attends a support group for testicular cancer victims and, after fooling them into thinking that he is a fellow victim, finds an emotional release that relieves his insomnia. He becomes addicted to attending support groups and pretending to be a victim, but the presence of another impostor—Marla Singer (Helena Bonham Carter)—disturbs him, so he negotiates with her to avoid their meeting at the same groups.