The Agnes de Souarcy Chronicles - Andrea H. Japp

The Season of the Beast
The Breath of the Rose
The Divine Blood

Originally written in French, these books tell the story of Agnes de Souarcy and her family, and the conspiracies swirling between medieval France and papal Rome. There's a knight, a lord, a convent full of nuns, the Inquisition, a boy who might not be a boy, ancient manuscripts, and murder.
The first two books were the strongest, the final third devolved into quasi-Da Vinci Code territory (which was rather disappointing), and got a bit tangled up in it's conspiracies. I liked the characters of Clement and Sister Anneline, resourceful and clever, and also the clerk Agnan, who was rather sweet. These are well written historical romps, the appendices at the back proving that there's some rather thorough research gone into writing the trilogy. I enjoyed reading these, although the ending was a little weak.