"Why, Cara, why did you do it?" "Maybe no one wants to see me as I really am. Maybe in this family it isn't all right to be different. And I am different, Kitty, whether anyone wants to admit it or not." "But, Cara,--it just seems like tonight you set out deliberately to cause trouble." "Even you don’t understand, do you, Kitty?" "I do, I mean I'm trying to. You're my twin, I want to understand!" "Yes, I know we're twins, but who am I?" demanded Cara hotly. "We're not like paper dolls cut out of the same cardboard!" Although identical in appearance, the Cameron twins were dramatically different in temperament. Cara, vivacious, adventurous. Kitty, sensitive, introspective. But these differences had never kept them from being each other's best friend, confidante, and close companion; that is -- until one fateful summer -- the summer everything changed. It began as a carefree vacation at Cape Cod; a summer filled with sailing, swimming, shell-searching, dances, and parties. But slowly Kitty starts to suspect that her twin is keeping something from her. Puzzled, hurt, and more than a little resentful, Kitty longs to find out what it is. But something hidden in her own heart prevents her from doing so, because Kitty has her own secret she cannot share.