"From the outside, the Chengs seem like poster children for the enduring promise of the American Dream. Once Patty landed a tech job near Dallas, she and Liang grew secure enough to have a second child, and to send for their first from his grandparents back in China. Isn't this what they sacrificed so much for, to be a family? But then little Annabel begins to sleepwalk at night, putting in motion a string of misunderstandings that strips away their...