On the trip to Tralfamadore, Billy Pilgrim reads Valley of the Dolls, which is the only English book available. He also looks at Tralfamadorian novels that he can't understand, but they are described to him as being comprised of brief messages describing a situation or scene, that when read simultaneously produce a surprising image of life. The saucer enters a time warp, and Billy is sent back to his childhood, looking over the Grand Canyon on a family trip with his parents. Billy hates the canyon, and is afraid he's going to fall in. Billy then time jumps to ten days later, still on family vacation but now visiting the Carlsbad Caverns, where the ranger turns out the lights and he experiences total darkness.

     Moving forward in time to the delousing station, Billy and his fellow prisoners re-dress, are entered into the prisoner ledger, and issued dog tags that can be snapped in half. If they die, one half will mark their body, and the other half will mark their grave. Two of the prisoners near Billy are Paul Lazzaro, a skinny car thief from Illinois who has promised to avenge Roland Weary, and Edgar Derby, a forty-four-year-old teacher from Indiana who pulled strings to get into the army at his age.

     The American prisoners are taken to a shed that, unlike the others they have passed, has fire and light inside. Singing Englishmen come bounding out to greet them. The Englishmen were among the first to be taken during the war, and have been prisoners for at least four years. Thanks to a clerical error early in the war, they have had extra supplies shipped to them by the Red Cross, and are stocked up with more than enough food. The Germans get along well with the English prisoners, and trade them building supplies in exchange for the coffee, chocolate and tobacco that the English have in abundance.

     Inside the shed, the English prisoners have set up a banquet for their new guests, and are surprised at how fatigued the Americans are. After they eat, the English put on a performance of Cinderella, during which Billy becomes hysterical and is taken to the hospital shed, where Edgar Derby volunteers to watch over him. Billy has morphine-induced dreams, and wakes up in a veterans' hospital in 1948. During his final year of optometry school, Billy has committed himself voluntarily to the hospital. The man whose bed is next to Billy's is Eliot Rosewater. Another veteran who mistakenly shot a fourteen-year-old fireman during the war, Rosewater introduces Billy to the science fiction writing of Kilgore Trout.

     Billy's mother is at the hospital to visit him. During her visits, Billy always hides under the covers, and so his mother speaks to Rosewater instead. Billy falls asleep under his blanket and wakes up back in the hospital during the war. An English colonel comes in to check on him, and Billy listens to Derby tell the colonel about how he was captured. Billy then travels back in time to the veterans' hospital. His mother has gone, and his fiancee, Valencia, is there to visit. Valencia is fat, ugly, and rich because her father owns the optometry school Billy attends. One of the reasons Billy knew he was going crazy was his asking Valencia to marry him.

     After having a conversation with Valencia and Rosewater, Billy travels in time to the zoo on Tralfamadore, where he has spent six Earthling months naked in a habitat, being viewed by thousands of Tralfamadorians. Billy goes about regular activities, eating, showering, exercising, all while a zoo guide lectures telepathically to visitors about his behaviors, and uses a machine to relay questions to Billy from the crowd. Billy has conversations with the Tralfamadorians about time, and they are baffled as to how he experiences time as singular moments in a linear chain, while they view all time as simultaneous. The explain to Billy that there is war on their planet too, but because they can't do anything about that time, they simply don't look at it.

     Travelling back in time to his wedding night to Valencia, Billy makes love to Valencia, impregnating her with their son Robert, and afterwards she questions him about the war. Billy gives vague answers, and soon after travels back to the prison hospital in 1944. High on morphine, Billy goes outside to urinate, and hears American soldiers in the latrine, violently ill from their welcome feast. When Billy returns to the hospital, he finds himself back in bed with Valencia on their honeymoon, then briefly on a train journey before the war, and then back to the prison hospital.

     Paul Lazzaro is brought in by Englishmen, after the one who played the Blue Fairy Godmother in their play broke his arm and knocked him unconscious for trying to steal his cigarettes. While they set his arm in a cast, a German major reads to his English friends writings about the German experience of enlisted Americans, as dirty, self-pitying, thieves. Billy falls asleep and wakes up in 1968, with his daughter Barbara chiding him for writing letters to the newspaper about Tralfamadore. Barbara makes Billy go to bed under his electric blanket. When she leaves, Billy time travels to the zoo on Tralfamadore, where movie star Montana Wildhack has been brought for him to mate with. Having been unconscious during her entire trip to Tralfamadore, Montana has had no interaction with the aliens, and is terrified. After a week of being on Tralfamadore, Montana asks Billy to sleep with her, and after he does, Billy travels in time to his bed in 1968, back under the electric blanket.

     The next morning, Billy goes back to work, much to the surprise of his staff. When examining his first patient, a boy whose father was killed in Vietnam, Billy tells him about Tralfamadore, and that his father is still alive in moments the boy will continue to see. At the complaint of the boy's mother, Billy is taken home from work.