Changeling (Order of Darkness book one), by Philippa Gregory
Luca Vero, the changeling. Or so the people of his village called him, for he was a very brilliant boy and his parents only peasants. The church of 1453 find him, always asking questions and put him to the task of Inquirer into some of the strange happenings the church has become aware of lately. He arrives at an abbey where the nuns are having visions and stigmata are appearing on their hands. All of these things began when the new abbess arrived but is she the evil temptress they think she is? Luca must discover the truth or watch an innocent girl burn at the stake.
Written by the renowned historical author of The Other Boleyn Girl and many other books, this is an easy read with interesting outcomes and images.