The Last Watch

This is a continuation of the story and its characters, but not part of the Day-, Night- and TwilightWatch books.
From Amazon.ca
While on holiday in Scotland, visiting a macabre tourist attraction, “The Dungeons of Edinburgh,” a young Russian tourist is murdered. As the police grapple with the fact that the cause of the young man’s 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, The Day Watch, and The Twilight Watch–is detailed to this seemingly mundane investigation, but on arriving in Scotland begins to realize that there is much more to the story than a wildcat vampire and a single murder.

Aided by Thomas, the head of Edinburgh’s 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.