Imagine the world after the First World War was over. Global spirit was crushed and everything seemed like it was covered with a veil of darkness. It was year 1921. At that very time, lots of people tried to use the situation and get money from people by telling them that they have the connections with "the other side". Some of the people, who were still in grief over their lost ones took the bait and got used by master con artists. Florence Cathcart (Rebecca Hall) was one of the most famous hoax exposers, who tried to help the police to catch those criminals. Her main goal was getting the con artists arrested and innocent people saved. At one point, she got invited to visit the boarding school for boys in Rookford. Headmaster put Robert Mallory (Dominic West) to deliver the message. Boys were frightened to death with the fact that years before, on that same property, there was a murder and that one of their friends, Walter Portman, had died recently. Since she arrived, students have been sent on vacation, as well as the most of the staff, leaving her alone with governess Maud (Imelda Staunton) and Robert. As she finds nothing, and decides to leave, strange things start to happen. Will she find anything and discover that ghosts actually exist?