If you are at all interested in 16th century European history this is probably not the book for you. If you enjoy crime fiction and whodunnits that play with the historical facts to make a good story, then you are in your element here.
Giordano Bruno, in his seventh adventure, has reached Prague and the court of Rudolf II, the Holy Roman Emperor. Prague is about as safe as it is possible for a city to be for those outside the faith of the Catholic Church, be they Lutherans, atheists, philosophers, alchemists, or Jews. Bruno arrives there on a mission from Francis Walsingham, Queen Elizabeth's spymaster, to find John Dee. Dr. Dee, among other things, is a spy and he has sent word to Walsingham that the Emperor is in grave danger. It is no secret that the Church wants Rudolf deposed and replaced by his loyally Catholic brother Matthias and Bruno must find out the truth behind the stories and rumours.
But John Dee has disappeared. Is he in hiding? Is he dead? Bruno and his young assistant Besler enter the lion's den to uncover the truth, quite literally as it turns out by the end. The author spends little time describing the milieu of Prague as a major urban centre in northern Europe, she concentrates on the five small areas relevant to the leading characters: the royal palace, the House of the Green Mound (the residence of Dr. Hajek where Bruno and Besler stay), Golden Lane (the location of Ziggi Bartos' home), the inn of the Winged Horse, and the Jewish Town.
It is the characters who turn a straight-forward plot of greed, theft, deception and murder into a lively adventure that holds the reader's interest through 460 pages. Emperor Rudolf is portrayed as an amiable man who is easily misled and somewhat gullible. Where other noblemen may have their cabinets of curiosities, Rudolf has a castle full along with an immense library of, mainly unread, arcane and theological volumes. Guiding him, or prowling around him, are his librarians Jacopo and Ottavio Strada, both of them not exactly adherents of the straight path, Thaddeus Hajek the court physician, the ingenious and financially stretched alchemist and inventor Ziggi Bartos (watch out for his eyes and tongue), the Spanish agent and Papal inquisitor Montalcino, and several others. Someone is a killer and Bruno must delve into their midst to ensure the Emperor is not the next victim.
In a plot that brings in all manner of violent crimes: murder, mutilation, child abduction, violent assault, will Bruno survive to the end? If he knew what his fate would be in the real world he may not have fought so hard to win through. But this was a fictional crime thriller, and a very good one.