Florence Cathcart (Rebecca Hall) has devoted her career to exposing claims of the supernatural. Schoolteacher Robert Mallory (Dominic West) approaches Florence to look into the death of one of his students. After multiple reported sightings of the young boy’s ghost from his schoolmates and some other eerie events, Florence decides to take on the case. Initially, the mystery surrounding the ghost appears to be nothing more than a schoolboy prank, but as Florence continues to investigate, she begins to believe that her reliance on science may not be enough to explain the strange phenomenon going on around her.