Leah and Nate, estranged siblings reunited after the death of their long-absent father, who bequeaths them his English country estate. Determined to leave their troubled past behind, they agree to sell the property. But when a mysterious woman named Ruth arrives, their plans unravel over the next terrifying twenty-four hours as they are besieged by an ominous cult — and hunted by someone, or something, lurking beneath.