The "Time Quintet" is a series of five science fiction novels written by Madeleine L'Engle. The series begins with "A Wrinkle in Time," published in 1962, and follows the adventures of Meg Murry, her brother Charles Wallace, and their friend Calvin O'Keefe as they travel through time and space to save their father and the universe from evil forces. The subsequent books, including "A Wind in the Door," "A Swiftly Tilting Planet," "Many Waters," and "An Acceptable Time," explore themes of love, courage, and the battle between good and evil. The series combines elements of fantasy, science, and philosophy, appealing to both young readers and adults.