The last remnants of humanity have fallen under threat to a mysterious group of creatures named 'the winged children'. Within one of the last cities, many young residents are designated to protect their people by capturing them to be studied by the city's researchers. Sorrel, a young woman who has been designated as one of the city's catchers, must face her fears as she begins to uncover secrets about her city and the threat which has made the lives of her companions and herself a living hell.