Blood Shadow: Book of Hartwell
This is the first book of the Blood Shadow new-age vampire series.
It is early 20th century San Francisco and the Black Death has taken over the city. Thomas Hartwell loses his wife and young son to the plague and is ready to take his own life, until someone knocks on his door and says, "Don't do it. I have a way that you will be able to see your wife and son again."