Shade is a young Silverwing bat, the runt of his colony. But he is determined to prove himself on the long and dangerous winter migration to Hibernaculum, millions of wingbeats to the south. During a torrential storm, Shade is swept away from his family, his friends, and the only life he has ever known. Alone and frightened as winter fast approaches and temperatures plunge, Shade must make a remarkable journey to rejoin his colony to the south.