The Black Nun of Bunnamairgie Friary, (Julia MacQuillan) lived in the 15th and 16th centuries in Ballycastle, Ireland (known then as Margeytown due to the proximity of the Margie River). She was called the "black" nun because of the color of the cloak (habit) that she wore. The nun's story unfolds as a present-day McQuillin (Cathleen) is searching for her family's history and travels to Ballycastle, to find out more. She comes across Julia's journal and the story of this beautiful young lass who is a mystic with prophetic visions. The visions eventually have repercussions for her in Margeytown village. Her benefactors, Count Randall and Countess Mary MacDonald, were historically long-time foes of the MacQuillins but become her friends.