Blood Maidens — Barbara Hambly

It's 1911. War is coming, and according to one of the vampires of St. Petersburg, the Kaiser is trying to recruit vampires. James Asher, Oxford don and formerly on His Majesty's Secret Service, is forced to team up again with his vampire partner Don Simon Ysidro for a journey to the subarctic Russian capital. Are they on the trail of a rogue vampire with a plan to achieve the power to walk in daylight? Asher wonders. Or is Ysidro's real agenda to seek the woman he once loved?