In his seaside home in Ilium, New York, middle-aged Billy Pilgrim writes a letter to the local newspaper describing his experience of having come “unstuck” in time. Despite his adult daughter Barbara’s skepticism, Billy insists that he is telling the truth and unable to control his leaps through time. In his letter to the newspaper, Billy also reveals that he has been kidnapped by aliens known as Tralfamadorians and, when not going back and forth between events in his life, lives in a comfortably furnished room under a glass dome on Tralfamadore as a zoo specimen paired with a voluptuous pin-up model, Montana Wildhack. In the winter of 1944, Billy, a young military chaplain’s assistant separated from his unit, finds himself in Belgium behind German lines with GIs Paul Lazzaro and Roland Weary. Suspicious of Billy, who has lost his dog tags and carries no weapon, Lazzaro develops an instant dislike of him. On Tralfamadore, Montana realizes Billy is “time tripping” and in order to distract him, seduces him. In Belgium, Lazarro and Weary, furious at Billy’s calm detachment, begin thrashing him, but the soldiers are soon interrupted and apprehended by a German patrol. After the war, on his wedding night, Billy hugs his new wife Valencia Merble, a sweet, plump woman who is amazed at her good luck in finding a husband and vows to Billy that she will lose weight. In the Belgian snow, Billy, Lazzaro and Weary join other American prisoners of war trudging through the local town, where Billy’s bedraggled condition provokes laughter among several prostitutes watching the passing procession. A German army photographer selects the compliant Billy to re-create his capture with three armed soldiers for a publicity photograph. After several years of marriage to Valencia, the couple has two children, Robert and Barbara, and Billy’s optometry business celebrates its success with the opening of his own office building. In Belgium, Lazzaro threatens Billy when he clumsily treads on Weary’s injured feet several times before the prisoners reach the train station. As the soldiers are loaded onto the boxcars, an unhinged American officer called Wild Bob Cody assures them they have served their country well. After the crowded train pulls away from the station, an older GI tells the others that their situation is mild compared to living through the Depression. Just after the war and before his marriage, Billy is in a mental hospital where his mother visits and tells Billy’s roommate, Eliot Rosewater, that she believes her son is suffering from having endured the horrific bombing of Dresden where he lost his best friend. On the train headed into Germany, Weary dies from his wounds and Lazzaro, who holds Billy responsible, swears vengeance. In the institution, Billy undergoes twelve sessions of electric shock treatment. Upon arriving at a prison camp in Germany, Billy is ostracized and given a woman’s overcoat and silver boots. American corporal and former high school teacher Edgar Derby befriends Billy and prevents Lazzaro from harassing him. As a child in Ilium, Billy goes to the community swimming pool with his father who vows to make a man of him, then flings Billy into the deep end of the pool where he sinks to the bottom. In Germany, Billy, Edgar and the others are marched to a camp where a group of British prisoners greet them enthusiastically. A cheerful British officer takes Billy aside to encourage him not to accept the petty humiliations of war and to wear his woman’s overcoat with dignity. Billy faints and wakes up lying on the lawn of his home in Ilium being licked profusely by a puppy that Billy names Spot. While Valencia proceeds to grow heavier over the years, Billy and Spot become fast friends, to his wife’s annoyance. One evening, Billy and Spot sit gazing at the stars when they are both drawn to a bright light in the sky that grows brighter and larger before abruptly disappearing. At the camp, Edgar admits that he volunteered to fight despite being forty-four and reveals he has a twenty-year-old enlisted son. On their twentieth wedding anniversary, Billy presents Valencia with a ring with a large diamond that he found in Belgium and she promises she will lose weight. Later that day, Billy finds his teenaged son Robert in the bathroom with a porn magazine that he confiscates, only to discover that the model pictured in the centerfold is Montana. Back at the POW camp, the British officers inform the Americans that they are to be transferred to the open city of Dresden where they will likely wait out the end of the war. When the GIs are asked to nominate a leader, Lazzaro volunteers until he learns that the leaders are often mistreated. Billy nominates Edgar who assumes his responsibility gravely. In Ilium, Billy accepts the position of presidency of his local Lions Club. That evening, Billy and Valencia meet with police after Robert has been picked up for vandalizing a cemetery. Billy, Edgar and the others then arrive in Dresden, which Billy likens to the fantasy city of “Oz.” Although Edgar approaches several officers to explain that he is in charge of the prisoners, he is ignored. When the Americans are marched through the city, an elderly German civilian is deeply offended by Billy’s attire and rushes forward to slap him. In New York, Valencia and Barbara see Billy, Valencia's father Lionel Merble, and others off on a chartered airplane flight to an optometrist convention. Just before take-off, Billy tells his father-in-law his premonition that they will crash, but Lionel, as well as the pilot, ignore him. Midway through the flight, the plane inexplicably goes into a dive and crashes. In Dresden, Billy and the others arrive at the local “Schlachthof,” or slaughterhouse, where they will be housed in building five. Edgar protests that the accommodations are against the Geneva Conventions, but is silenced. Rescuers find Billy, the sole survivor of the plane crash, bloodied in the snow. When Valencia learns of the accident, she jumps hysterically into her Cadillac and races off to the hospital, causing several minor accidents en route, one of which dislodges her car’s exhaust pipe. Upon reaching the hospital, Valencia collapses and later dies from carbon monoxide poisoning. After brain surgery saves Billy, he recovers in a hospital room shared with writer Bertram Copeland Rumfoord who discusses his latest book on the Dresden fire bombing with his visiting daughter Lily. When a revived Billy reveals he was in Dresden during the raid, Rumfoord refuses to talk about it and advises Billy to write his own book. On the night of 13 February 1945, the POWs are visited by an American member of the German Ministry of Propaganda, Howard W. Campbell, Jr., who announces that the Germans are America’s friends and can help them battle the real enemy, the Communists. An air raid siren interrupts Campbell’s speech and the men take refuge in the shelter during the fierce, long raid. The next morning Billy and the other prisoners are forced to dig through the smoking rubble of the city to find and burn dead bodies. Recovering at home alone with Spot, Billy receives a visit from Robert who is now a Green Beret officer about to return to his unit in Vietnam. Robert expresses sadness over Valencia’s death and promises to make it up to Billy for his recklessness as a teenager. After Robert departs, Billy and Spot gaze out at the night stars and watch a light that grows increasingly brighter, then surrounds the pair and transports them to the domed room on Tralfamadore. Although Billy cannot see the aliens, they are able to speak English and welcome him and Spot to their new home. When Billy cautiously expresses pleasure at his surroundings and asks if he can leave of his own free will, the aliens express amazement that nowhere in the universe but Earth is there a discussion of “free will.” In the burning remains of Dresden, Billy reflects that it seems like the end of the world, but the Tralfamadorians assure him that Earth does not cause its own end, but is annihilated with the rest of the universe when the Tralfamadorians accidentally ignite a new kind of fuel. Eager to witness Billy reproduce, the Tralfamadorians present him with Montana who, although initially terrorized, soon adapts to the domed room, Billy and Spot. While Billy and Edgar continue to clear the rubble searching for bodies, Edgar comes upon an intact figurine similar to one his son broke at home years before. Delighted, Edgar shows it to Billy, but moments later the SS guards pull him aside, accuse him of theft and, to Billy’s horror, immediately execute him. The Tralfamadorians advise Billy the best way to enjoy eternity is to ignore the bad times and concentrate on the good. Barbara and her husband Stanley remain concerned over Billy’s revelations about Tralfamadore and are disconcerted when he confides that Montana is pregnant. Stan asks Billy if he knows when he will die and Billy acknowledges that he has seen his death numerous times. He reveals that while giving a lecture about Tralfamadore in a nearby city, the crazed Lazzaro assassinates him, but he has no fear as he knows he will live again. After the Russians liberate the prisoners in Dresden, Lazzaro presses Billy to help him and his friends pillage unoccupied shops. While carrying away a large grandfather clock, the GIs are frightened off by approaching Russian soldiers and flee, leaving Billy pinned under the heavy clock. On Tralfamadore, Montana gives birth to a baby boy whom she names Billy and to celebrate, the aliens shower the dome with fireworks.