A university student (Sam Claflin) and some classmates are recruited to carry out a private experiment — to create a poltergeist. Their subject: an alluring, but dangerously disturbed young woman (Olivia Cooke). Their quest: to explore the dark energy that her damaged psyche might manifest. As the experiment unravels along with their sanity, the rogue PHD students are soon confronted with a terrifying reality: they have triggered an unspeakable force with a power beyond all explanation.