A Swiftly Tilting Planet by Madeleine L'Engle
Paperback. Condition: Good-. 1980. Dell. 5th Printing.
Fifteen-year-old Charles Wallace and the unicorn Gaudior embark on a journey through time and peril to prevent the destruction of the world by the mad dictator Madog Branzillo.
Book #3 in the Time Quintet. Early edition.