Doctor Who: Dark Horizons

On a windswept Northern shore, at the very tip of what will one day become Scotland, the islanders believe the worst they have to fear is a Viking attack. Then the burning comes. They cannot run from it. Water will not stop it. It consumes everything - yet the burned still speak. The Doctor is looking for a game on the famous Lewis chess set. Instead he encounters a people under attack from a power they cannot possibly understand. They have no weapons, no strategy and no protection against ...