On a chilly November afternoon, six-year-old Luke Nightingale’s life changes forever. On the playground across from the Metropolitan Museum of Art, he encounters Daniel. Soon the boys are hiding from dinosaurs and shooting sniper rifles. Within hours, Luke and his mother, Claire, are welcoming Daniel into their Upper East Side apartment—and their lives. Daniel and Luke are soon inseparable. With his parents divorcing, Luke takes comfort in having a near-constant playmate. But there’s something strange about Daniel, who is more than happy to bind himself to the Nightingales. The divorce has cut Luke’s father out of the picture, and as his increasingly fragile mother struggles with the insidious family depression, Daniel—shrewd, adventurous, and insightful—provides Luke both recreation and refuge.