After a falling-out with his father, Reginald de Brune travels to St. Michael's Monastery for a short stay. There, one night at midnight, he observes a beautiful young woman, Christabelle, swearing a mysterious vow at the altar. The two quickly fall in love, but Christabelle's father has other plans, deciding to immure her in a convent, where she is terrorized by a cruel abbess.

But there is more to both Reginald and Christabelle than meets the eye, and quickly the two find themselves caught up in the intrigues of Henry II, his queen, Eleanor of Aquitaine, and their two warring sons,...