Ten years ago, an impossible thing happened: a flock of pigeons picked up a human baby who had been abandoned in an empty lot and carried her, bundled in blankets, to their roof. Coo has lived her entire life on the rooftop with the pigeons who saved her. But when a hungry hawk nearly kills one of her flock Coo must make a perilous trip to the ground for the first time to find Tully, a retired postal worker who can heal injured birds. Living with Tully, Coo experiences warmth, safety, and human relationships for the first time. But just as Coo is beginning to blossom, she learns the human world is infinitely more complex and cruel than she could have imagined.