When seventeen-year-old Molly Gibson’s widowed father remarries, her life is turned upside down by the arrival of her vain, manipulative stepmother. She also acquires an intriguing new stepsister, Cynthia, glamorous, sophisticated and irresistible to every man she meets. The two girls begin to confide in one another and Molly soon finds herself a go-between in Cynthia’s love affairs – but in doing so risks losing both her own reputation and the man she secretly loves.