The Queen's Man by Sharon Kay Penman is the first of four books in her Justin de Quincy series. These are mysteries set in England in the 1190's. The main character, Justin de Quincy, is sworn to serve Queen Eleanor of Aquitaine and his service takes him into danger at every turn.
I love this author's historical fiction. I have read all but a few of her novels and they are all wonderful. I already plan to read the rest.