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.