Jared Harris and Sam Claflin star in this British horror film inspired by real events. In the 1970s Professor Coupland (Harris) encourages a group of his university students, which includes Brian McNeil (Claflin), to undertake a dangerous experiment. To test the theory that poltergeists are created by negative human energy, Brian and his fellow students use a disturbed patient as their subject. However, the results of the experiment prove to be both terrifying and deadly. The film also stars Olivia Cooke and Erin Richards.