The granddaughters of the author Madeline L'Engle draw on previously unshared archival materials, including photographs, letters, and journal entries, to explore her literary life, legacy and impact on friends, fans, and family members.

One night, thirteen-year-old Meg Murry meets an eccentric new neighbor, Mrs Whatsit, who refers to something called a tesseract. She later finds out it is a scientific concept her father was working on before his mysterious disappearance. The following day, Meg, her child genius brother Charles, and fellow schoolmate Calvin visit Mrs Whatsit's home, where the equally strange Mrs Who and the unseen voice of Mrs Which promise to help Meg find and rescue...