This is the sequel/prequel to Goth Opera, though the books are written by different authors. I do suspect, though, that there are some strict guidelines for the authors to follow, especially in a series such as the Doctor Who series. While the relationship to the TV show is open to interpretation, for those who like Doctor Who, and vampires, this book is a good waste of time. As well as Goth Opera, the book is also connected with the serial The Five Doctors, where the antagonist is trapped in the Tomb of Rassilon at the conclusion, and also The State of Decay, where one of the Doctor's companions travels to the planet and meets up with Romana II.
It has been a long time since I read this book, however it is good that a number of people on Goodreads have provided detailed reviews, which enables me to trigger my memories as to this book. Then again, since it is pretty much a cookie cutter novel, I generally do not retain detailed memories of the plot (though I tend to remember the TV series somewhat more, but then I suspect it is because of the visual medium, and also that I so loved the original series that I have watched them multiple times).
This story is split between 1920's Chicago, where the Doctor meets up with a private eye who is investigating some murders, and it turns out that the murderers are vampires, and the planet where the State of Decay is set. It is suggested by those who have read the book that this division was managed quite well, particularly since when the Doctor's companions split (and they do quite often) there usually is one story arc which enthrals the reader, while the second story arc is somewhat ho-hum. Apparently this is not the case in this book, though of the books that I have read, the story arcs tended not to be very ho-hum.
The antagonist isn't a vampire, but an elemental beast that feeds on misery and suffering. I am unsure of the connection between the two arcs (beyond that they both involve vampires) and as I have mentioned elsewhere, I do find vampires to be quite boring. However I did enjoy the State of Decay, namely because I found that the castle in which the story was set was actually a crashed spaceship and over the eons since they had arrived, a feudal society had arisen on the planets, though while the peasants were human, the overlords were vampires. Vampires and spaceships? Personally I am not really sure if that does work.