After a holiday accident that nearly kills her, 32-year old Emily and her husband Freddie move from London into Larkin Lodge, a beautiful country house on remote Dartmoor, far away from their lives and friends in London. It should help heal her and be a wonderful fresh start but soon after moving in, Emily starts to feel that there's something wrong.

There's a terrible presence emanating from the room on the third floor. While Freddie doesn't sense anything wrong, Emily can't bear to even step across the threshold, and as the darkness she feels in the room upstairs spreads like mould further into the building, and strange occurrences start happening, Emily becomes convinced that someone was murdered in the house and is now haunting it.

But there are no records of any one ever dying in the property, not even old in their beds. In fact, it's been a happy home for all who've lived here. Except, it seems, for them. Ever since they moved into the house, their marriage has started to crumble. There's a sense of distrust. With Freddie growing distant and irritable and dismissing her concerns about the house as part of her post-sepsis syndrome, and with cracks in their relationship building with each day, Emily starts doing some digging into the secrets of Larkin Lodge and the locals who've lived there.

But how can she solve a murder that never happened? And can she solve it in time to prevent another?