In a Polish shtetl, two young men who have grown up together betrothe their unborn children, ignoring the advice of a mysterious traveler not to pledge the lives of future generations. Soon after, one of them dies, and the wife of the other dies in childbirth. The children grow up in different towns, without ever knowing of the betrothal, but the power of the vow leads them to meet each other when they are marriageable. The young woman, Leah, is promised to another man, but Channon, the son of the father who died, is a practitioner of mysticism, and seeks to win his bride through sorcery.