This book ties into The Vampire's Christmas Surprise
Adam was turned against his will in 1920 and was forced to leave behind his wife and young son for fear of killing them in his need to feed. Nearly a century later, he wants to know what became of his family and if he has any descendants left in the world. Puck, the alpha werewolf letting him live in his territory, knows a great investigator, but Adam has been warned- Lucius doesn't play by anyone's rules but his own, and he'll ask for a price that has nothing to do with money.
Lucius is interested in helping Adam. He's always up for solving a good mystery, but when things turn romantic, Lucius quickly realizes Adam isn't interested in casual sex. Too bad that's been a pillar of Lucius's existence for years. Pleasure has never been complicated for him, but this vampire seems interested in getting him to change his ways