In an upmarket apartment block in Knightsbridge called Barrington House, the door to apartment 16 is always locked. For the last twenty years it has been empty. No one goes in. No one comes out. One evening a night security guard hears noises from inside. What he sees through the letterbox of apartment 16 changes his life forever... Shortly after a young American woman, Apryl, arrives at Barrington House. She's been left another apartment in the block by her Aunt Lillian — an aunt she never knew, who died in mysterious circumstances. Touched by her aunt's story Apryl delves into the history of Barrington House. Something bad happened — something dark... something terrible, and the only way to stop it is to confront whatever lies behind the door of apartment 16 the gateway to something altogether more terrifying...