In this companion volume to A Wrinkle in Time (Newbery Award winner) and A Wind in the Door, fifteen-year-old Charles Wallace and the unicorn Gaudior undertake a perilous journey through time in a desperate attempt to stop the destruction of the world by the mad dictator Madog Branzillo. They are not alone in their quest. Charles Wallace's sister, Meg — grown and expecting her first child, but still able to enter her brother's thoughts and emotions by "kything" — goes with him in spirit.