Rupert Brown (Eric Taslitz) and Amelia Daley (Nancy McKeon) are classmates who discover that their substitute teacher, Miss Switch (Janet Waldo), is a witch complete with a magical talking cat named Bathsheba (June Foray). She tells the children that the wicked witch Saturna has taken control of the Witches' Council and has condemned the fair Miss Switch with the aid of her Computer Witch.