In a secluded estate outside London in the decadent 1920s, headstrong and promiscuous Victoria Ameranthy is beginning to wonder if she has made a terrible mistake. By day, her charming new husband, Sebastian, is wickedly handsome, independently wealthy, and an absolute beast in the bedroom. But after the sun sets, he becomes a man of many secrets, conducting his business in the shadows and disappearing for hours in the middle of the night. When Sebastian returns one evening, accompanied by his business partners and hauling a man in shackles to the cellar, Victoria and her impish younger brother Reginald decide to investigate. They have no inkling that opening the locked door will lift the veil between their privileged lifestyle and the darkness that lurks all around it, hungrily stalking its prey. And neither of them are prepared for what happens when the clock strikes midnight.