Her Highness' First Murder (Five Star Mystery Series)

When headless corpses begin appearing on the streets of London, Elizabeth Tudor is as shocked as everyone else. When one of her own ladies is murdered, Elizabeth joins with new friend Simon Maldon to find the killer. Henry VIII, also shocked by the murders assigns one of his Welsh guardsmen, Hugh, to investigate, since the women are dressed as nuns and might signal new religious troubles.
Suspects include a madman, a courtier, a reformer, a well-known criminal, and others, even Elizabeth's castellan. Simon, discovering that he is good at the art of disguise, plays various parts as he works at narrowing the list.
Elizabeth's part in the investigation is kept secret from the king, who would certainly not approve. But it cannot be kept secret from the killer, and in the end, he turns his attention to them. Simon, Elizabeth, and Hugh face a murderer who is beyond caring how many die, as long as he gets what he wants.