The Last Watch - Sergei Lukyanenko

While on holiday in Scotland, visiting a macabre tourist attraction, The Dungeons of Edinburgh, a young Russian tourist is murdered. As the police grapples with the fact that the cause of the young mans death was a massive loss of blood, the Watches are immediately aware that there is a renegade vampire on the loose. Anton the hero of The Night Watch and The Day Watch - is detailed to this seemingly mundane investigation, but on arriving in Scotland begins to realise that there is much more to the story than a wildcat vampire and a single murder.Aided by Thomas, the head of Edinburghs Night Watch, Anton investigates and ruminates, and becomes aware that a team of unlicensed Others are hunting for a fabled magical treasure, hidden in the sixth level of the Twilight by Merlin himself