The runaway New York Times bestseller--over half a million copies in print It happens quietly one hot August morning in Iowa: two families awaken to find their little girls have gone missing in the night. Seven-year-old Calli Clark suffers from selective mutism brought on by a tragedy when she was a toddler. Petra Gregory is Calli's best friend--and her voice. But neither girl has been heard from since they vanished. Now, Calli and Petra's parents are tied by the question of what happened to their children. And the answer is trapped in the silence of unspoken family secrets.