It was just a patch of ice. But it was nearly enough to kill Kath Redway, spinning her car into Burrator Reservoir in the beautiful Dartmoor National Park. She is shocked but delighted to escape with a few bruises and amnesia. But her family is not so pleased. Her handsome husband is cold, even angry. Her gifted daughter talks ever more strangely, about a 'man on the moor'. Then, as chilling fragments of memory return, Kath realizes her 'accident' was nothing of the kind. And now her life collapses into a new world of darkness, menace, and terror.