This is the eighth book of the adventures of Sister Fidelma, but it's the only one I happen to have read. It stands perfectly well by itself and doesn't require any knowledge of the preceding books.
Sister Fidelma lived in Ireland in the 7th century, an unfamiliar and interesting social environment for me, and probably for you as well. Ireland was divided into various kingdoms operating under a common body of law. Unexpectedly, it offered a large measure of equality to women, who could practise any profession alongside men and had full legal rights. Furthermore, Irish Christianity had no interest in celibacy: the clergy could marry and have children, and normally lived in communities of both sexes.
Sister Fidelma is a kind of nun, but she's also a kind of lawyer/detective. Furthermore, she's the sister of the King of Munan, who reigns over about a fifth of Ireland; but she generally prefers to keep quiet about that.
In this book she goes by ship on a pilgrimage to Spain with a bunch of other pilgrims, known to each other but not to her. As well as the usual dangers of a sea voyage at that time, it turns out that there's a murderer on board, and Sister Fidelma takes on the job of identifying him or her.
Fidelma is quite a well-drawn character. She's intellectual and clever, but she has weaknesses, and she's pleasant enough to other people to be generally liked.
Overall, I quite liked the book, and would happily read more books in the series if they were lying around and I had nothing better to do; but I wasn't so gripped that I want to rush out and buy more of them. The setting is interesting and the characterization is competent, but the story seems somewhat implausible, both in general and in certain specific details. The plot is serviceable but not really fascinating.
If you just want a detective story, this is not a bad one but you could surely find better. The main attraction of the series is the unusual 7th-century setting.
Written in October 2007