Meg Murry and her friends become involved with unearthly strangers and a search for Meg's father, who has disappeared while engaged in secret work for the government.
After her mother leaves home suddenly, thirteen-year-old Sal and her grandparents take a car trip retracing her mother's route. Along the way, Sal recounts the story of her friend Phoebe, whose mother also left.
A troublesome twelve-year-old orphan, staying with an elderly artist who needs her, remembers the only other time she was happy in a foster home, with a family that truly seemed to care about her.