In Mallory, New York, as five sisters, aged eleven to seventeen, deal with assorted problems, conflicts, fears, and yearnings, a mysterious middle-aged man watches them, fascinated, deciding which one he likes the best.

Identical twins Meredith and Mallory Brynn have always shared one another's thoughts, even as they dream, but their connection diminishes as they approach their thirteenth birthday, and one begins to see the future, the other the past, leading them to discover that a high school student they know is doing horrible things that place the twins, and others, in grave danger.