A new killer is afoot on the streets of Sherlock Holmes-era London. The difference is that this killer is targeting London's vampires, who have existed in the city for several hundred years. Someone, or something, is opening their coffins during the day, thereby exposing them to sunlight, and certain death.
Simon Ysidro, London's oldest vampire, enlists the help of James Asher, an instructor at Oxford University, and former British spy, to investigate. Asher is given little choice in the matter. Any non-cooperation or attempts at double-crossing on Asher's part will lead to his young wife, Lydia, a medical doctor, becoming the newest member of London's vampire population.
Taking great pains to keep Lydia as safe as possible, Asher and Ysidro visit the now-empty coffins, looking for clues. Ysidro is less than cooperative, not wanting to reveal too much as possible about life as a vampire. Lydia undertakes her own investigation, looking for anomalies in house ownership records, or people who have lived much longer than normal, while spending her nights reading medical journals.
Asher learns that turning someone into a vampire is not as easy as just drinking their blood. More than that is involved, and it does not work all the time. Asher and Ysidro travel to Paris, where they meet Brother Anthony, a very old and frail-looking vampire who lives underground in the Catacombs. Asher also narrowly escapes getting his blood drained by several French vampires.
Returning to London, Asher learns that Lydia, increasingly concerned about his lack of communication, has taken matters into her own hands. Does Asher find her in time? Is the culprit found and stopped? Does this have anything to do with a sudden rash of "unexplained" deaths in London, whose victims have had their blood drained?
This is a really good novel, but not a very fast moving novel. It will take some effort on the part of the reader, but that effort will be rewarded, because Hambly shows that she knows how to tell a story. It is worth checking out.