For two years, the near-future space ship St. Louis has searched in vain for a habitable planet. After a ghostly woman appears to a ten-year-old passenger, she begins to question the nature of their quest. Their spacecraft, the woman informs her, was named for a ship full of Jewish refugees, refused from its destination in Cuba, which was forced to return to Nazi-occupied Europe. Understanding the parallels in their story, the child discovers that her life on the ship is part of a simulation to keep the passengers occupied as they search for a planet that is unlikely to exist. With the help of the woman, she is able to wake up, once again becoming an adult programmer, and change the ship's course back to an uncertain future on Earth.