It was the night she almost died. Jane Trevally, newly divorced and feeling a little lost, agrees to accompany a man she doesn't know to his house in the darkest corner of Hampstead Heath. She's offered a drink, goes in, and then - a scream and the sound of something falling upstairs - Jane senses she's in a bad place. She runs. Twenty five years later, Jane finds herself outside the same house, this time to return a small white dog who's been found near her home in the country; a dog whose owner has just been reported missing. A fleeting glimpse of a haunted looking woman through the window sends Jane on a mission to uncover the house's secrets - secrets more terrifying than she could have ever imagined, especially when she realises it could have been her. . .