This is one of Tremayne’s Sister Fidelma mysteries; he also
writes about the history of the Celts under the name of Peter Berresford
Ellis.

Fidelma of Cashel is the sister of the King of Cashel and a highly educated
advocate of the Brehon laws in Ireland in the 7th century AD. She speaks three
or four languages, can read and write and has studied law for eight years in
a bardic school in Tara, the central kingdom of Ireland and domain of the High
King. She also is a member of the religious community of the St. Brigid of
Kildare. The community that she belongs to is very different from the
monasticism that later developed in Europe with celibacy and cloistering as
basic tenets. The Irish church had developed separately from Rome during the
early part of the millennium and had adapted to the cultural values of the
Irish Celtic society. Tremayne, by the way, includes an excellent
introduction giving some of the background of tensions between Irish
Catholicism and Roman Catholicism that creates a lot of the tension in the
book. Fidelma has not taken vows of celibacy, nor has she entered a
cloistered community so she is available to lend her assistance as an
Advocate of the Courts when a legal issue, such as murder, comes up.

In this book, set in 666 AD, she is called to an Abbey on the far west coast
of Ireland to investigate the murder of a young woman. She has been found
hung from the well rope in the Abbey’s well, naked and beheaded. No one
claims to be able to identify the body without the head and no one has
reported a woman missing in the near vicinity. Fidelma is called in to
investigate and try to figure out who the girl is and who killed and left
her in such a ghastly way.

That’s the main plot. The subplot involves Brother Eadulf, a Saxon monk who
adheres to the Roman Catholic tradition and usually acts as Fidelma’s
sidekick in her investigations, providing a counterpoint to her theological
beliefs and the slightest hint of love interest. On the sea voyage to the
Abbey, the ship she is on discovers a Gaulish ship floating abandoned at
sea, with a missal Fidelma has given to Eadulf in one of the cabins. She had
left him in Rome and is beside herself with worry, especially after finding
blood on the deck of the ship.

The Sister Fidelma series is generally pretty good. The early ones are a
little spotty in the strength of the plot lines and Tremayne has an
irritating tendency to explain Fidelma’s credentials more than is needed,
but essentially they read well and are interesting. The historical detail is
fascinating without intruding too much on the action. I’m looking forward to
finding a few more of these.