In 1984, Celestine Tolland was a fifteen-year-old member of a crew of explorers who set off into space, but a virus killed nearly everyone on board the Phaeacia. After two years, the survivors made it home. However, because they were traveling near the speed of light, an effect called time dilation meant that more than thirty years had passed on Earth. Celestine had been a high school freshman in 1984, but returns to Earth to begin her senior year in 2022. While she is still only seventeen, her former classmates are nearly fifty years old. Celestine faces the typical teenage trials, but also survivor's guilt, fear of a government conspiracy, and fear of falling ill, all while living with the threat of being committed to in-patient psychiatric care, among neighbors who fear she's contagious.