Twelve-year-old Twig is a talented Dreamer, although her mother has discouraged her from exploring her powers. When Twig begins to have recurring nightmares about a green light exploding from the sky and causing havoc for her people, she, must find the courage to defy her mother and learn to be a Dreamer. Helping Twig on her quest are her best friend, Greyhawk, and Screech Owl, a shaman who has been banished from the village. Together, they must convince their people of the danger from the sky as well as the environmental changes that will devastate their world and force them on a great westward migration to the mysterious Duskland, far from the only home they've ever known.