It is thirty years after the Darkening, the cataclysmic event which shattered the world and the electric grid. In what was America, small towns and communities have rebuilt in that time. At the edge of the mountain town of West Rise, Lucas and his dog, Virgil, live in an old fire lookout, where Lucas works as a signal keeper, communicating by light with the town across a deadly river. The lights of the town across the river have always been a source of comfort and reassurance, a glimpse of normalcy in an ever-changed world, including to a young woman Shannon, a member of the local militia. When the lights across the river suddenly go out, Lucas, Shannon, and Virgil must venture across the water to determine what has happened - and what dangers their own town might face.