Billy is released from the hospital and opts to live alone, over the objections of Barbara. Robert has reformed and enlisted for the Vietnam War. While alone, Billy is abducted to the alien planet of Tralfamadore, along with film actress Montana Wildhack. The Tralfamadorians live in the "fourth dimension" and teach Billy the universe is made up of random moments strung together; when one dies, they go back to another point in their life, and it is up to them to focus on good moments and ignore the bad. The Tralfamadorians hope Billy and Montana will mate. Billy and Montana fall in love and have a child, whom Montana names Billy Jr. On Earth, Billy argues with Barbara about the existence of Tralfamadore; Billy, being able to travel into the future as well as the past, shares a vision of his death, in which he is shot by an elderly Lazzaro while giving a speech about Tralfamadore.