It is the week before Christmas and the cathedral city of St Albans is blanketed by snow. But beneath the festive lights, darkness is stirring. The frozen body of a young girl is discovered by the ice-covered lake. The police scramble for clues. A local woman, Jenny, has had visions of what happened the night of the murder. But Jenny is an exhausted new mother, whose midnight wanderings pull her ever closer to the lake. Can Jenny be trusted? What does she really know? Then another girl goes missing, and the community unravels. Neighbour turns against neighbour, and Jenny has no idea who to believe. As Christmas Eve approaches, Jenny discovers a secret about her past - and why she could be key to everything...