"One night, Louisa and her father take a walk on the beach. He's carrying a flashlight. He cannot swim. Later Louisa is found washed up by the tide, barely alive. Her father is gone. She is ten years old. In chapters that shift from one member to the next, turning back again and again to that night by the sea, Susan Choi's Flashlight chases the shockwaves of one family's catastrophe. Louisa is an only child of parents who have severed themselves from...