After a tornado ravages a small town in South Dakota, Tammy Richards, a former Marine turned schoolteacher, finds herself in a school basement, crushed under the rubble. She tells her trapped students to "follow the angels." Succumbing to her wounds and blacking out, Tammy awakens in a hidden world. She discovers men and women who risk their lives to help people. They have a startlingly advanced technology in this utopian world. However, not all is as it seems.