A Swiftly Tilting Planet by Madeleine L’Engle starts with the Murray family holding their usual Thanksgiving party. Branwen Maddox O’Keefe, the ever argumentative and uncooperative lady, is among the people who attend the dinner party. Mrs. O’Keefe’s son, Calvin O’Keefe, is married to Meg from the Murray family. During the party, the president of America calls Mr. Murray to inform him that Mad Dog Branzillo is planning to launch nuclear weapons at America. Mrs. O’Keefe suggests that Charles Wallace should assume the responsibility and ensure that peace exists between the U.S and South America.
Charles and Meg have telepathy abilities, and they decide to keep close to each other. When Charles repeats the lines in Mrs. O’Keefe’s poem, a unicorn known as Gaudior greets him. Gaudior tells Charles that they have to travel into the past to understand why nuclear threat appears in future. The two men start the journey but are almost stopped by Echthroi. Meg helps the duo severally to escape the wrath of Echthroi. Through the journey, Charles discovers that many spirits work in the world over different periods of time.
Charles’ objective was to find the “might have been” and understand how they can help him to change future disasters. He goes through many lives of people, including Mathew Maddox. On the other hand, Meg uses this opportunity to unravel the lineage of people close to her. Generally, the book shows how love and patience can make people live in harmony.