Novel by Newbury Award winning author Madeleine l'Engle. A Swiftly Tilting Planet takes place several years after the events in A Wrinkle in Time and A Wind in the Door. Meg Murray, the protagonist in those novels, is now an adult married to childhood sweetheart Calvin O'Keefe. Meg returns home for the thanksgiving holiday and is overjoyed to see her little brother, the enigmatic genius Charles Wallace. Meg and Charles share a special bond stemming from their childhood adventures.

The Murray family soon learns that the world is being threatened by insane dictator Mad Dog Branzillo. Charles Wallace undergoes a desperate quest through time and space to stop Branzillo's threats of nuclear war with the help of Gaudior, a time-shifting unicorn and Meg Murray who accompanies Charles by kything (an ability somewhat analogous to telepathy).

Although somewhat dated (the novel has a definite Cold War feel and several references are made to the cuban missile crisis). The novel is still an interesting read and skillfully combines historical settings, emotional context and joy in the human spirit.