The narrator of the story is an entity who lives inside a man named Tod Friendly. He is a bystander and cannot control what Tod says or does in any way. The narrator sees Tod's life progressing backwards-from death to birth. He comes into consciousness with Tod's death and learns to translate reverse speech. Most life events confuse him because he sees them occurring backwards. He sees Tod getting stronger and more virile as he recovers and grows noticeably younger.

Tod "starts" a long-term relationship with a woman named Irene, which commences with her leaving him for good. Again, the narrator is trying to rationalize the reverse events in the tumultuous relationship. He works as a doctor and his actions to help people are viewed as hurtful by the narrator because people come to him well and leave sick and in pain. Tod seems to be a tortured man; he has nightmares about doctors and babies. He has a sordid past that he is running from. The narrator has an intuitive grasp of this and also knows that life can't be altered because suicide is not possible.

Tod's name changes to John Young. John is living in New York and is tipped off by Nicholas Kreditor that the authorities are aware of him, so he changes his identity to Tod. John's life gets better while he is still living quietly in the country. He is a popular doctor and has many friends. He is a womanizer and has many girlfriends, including Irene. The narrator is very disturbed by John's work at the hospital. He works traumatic cases which, when viewed in reverse, are interpreted by the narrator as John hurting people.

John leaves for Europe to fight in the war although in actuality, he is fleeing Europe to travel to America. His name changes to Hamilton de Souza while he lives in Portugal for a short time. He then travels through Europe to Italy, and finally back to Germany where his name is Odilo Unverdorben.

Odilo works at Auschwitz, where the narrator sees his work as magical. In his view, they are bringing thousands of people back to life. He works closely with a character named "Uncle Pepi" in the experimentation rooms. His wife Herta, does not approve of his work. Their child, Eva dies shortly after birth.

Odilo works at "lesser" facilities which "process" unwanted people like the insane and blind. The narrator is upset by the decline in "great work." His relationship with Herta grows more intense as they move towards their marriage, then fades as they get to know each other. Odilo then is back at medical school, where he meets Herta. He moves home with his family and becomes a child. The narrator is upset knowing his life will end at Odilo's birth.