Forced to leave their own planet when their sun collides with it, a group of aliens crash-land on Earth and establish a base in Witch Mountain. Later, two of its young members, Tia and Tony, leave the security of their colony to search for others of their kind. During their trek they befriend Jason O'Day, a kindly Earthling who rescues them from Aristotle Bolt, a billionaire who is seeking Tia and Tony--and their extraordinary powers--which he plans to use to control the world. In this third entry (preceded by two features: "Escape to Witch Mountain," 1975, and "Return from Witch Mountain," 1978) the saga continues as Jason, Tia, and Tony attempt to escape from Aristotle Bolt. The pilot also depicts the trio's efforts to help Uncle Bene, the space traveler, find his grandson.