Clumsy,put-upon Ruth Patchett leads a drudge's life with her two demanding children and her neglectful accountant husband Bobbo. When Bobbo starts an affair with his top client,the glamorous,lighthouse-dwelling romantic novelist Mary Fisher, Ruth does everything she can to be a good wife but everything fails and Bobbo humiliates her in front of his parents before leaving her for Mary. Finally Ruth snaps and,declaring that she will become a she-devil,burns the house down in such a way that the insurance claim will be invalid and dumps the children on Mary and Bobbo.