Duchess of Cornwall Close: sheltered accommodation, a mix of bungalows and flats, newly built and not quite finished. Despite the bitterly cold weather, elderly residents are moving in. They don't notice the figure in the shadows. Someone who doesn't mind the cold.

Then, one snowy night, an old lady is murdered - dragged from her bed and strangled with a length of flex.

DCS Simon Serrailler and his team are aware of bizarre circumstances surrounding her death - but they keep some of these details secret, while they desperately search for a match. All they know is that the killer will strike again, and will once more leave the same tell-tale signature.