Katherine Winter (Hilary Swank) was doing Catholic missionary work in Sudan with her husband and daughter who became victims of the angered locals who believed that the long drought conditions in their region was because of their presence. Due to this incident, Katherine loses faith in God and joins Louisiana State University as a professor. She starts debunking religious phenomena and exposing the scientific facts causing them. This activity makes her famous for debunking mis beliefs around the world. Katherine is invited to a small town called Haven located on the outlet of a river that turned into blood after the death of a child. She goes there with her associate Ben (Idris Elba) to investigate the matter. While she is there, the ten biblical plagues seem to happen all over the town. Despite of confusions, she manages to discover the cause of the evil happenings.