In the small town of Merwin, Mississippi, Miriam is an outcast. Her father abuses her, she lives in crushing poverty, and the townsfolk disdain her. Only her faith in God sustains her, so when she hears the voice of God telling her that her child will be the second coming of Jesus, she rejoices. Her joy is short lived when she discovers her archrival, the town doctor's wife, Sarah, is also pregnant. To Miriam's surprise, both babies are born female.

Miriam's daughter, Marianne, and her rival's daughter, Lovey, have very different childhoods. Marianne remains poor in Merwin, while a distant, wealthy relative raises Lovey. Through it all, Miriam remains convinced that God has special plans for her family. When Marianne delivers a baby boy, Miriam is convinced that he is the long-awaited messiah. She dedicates her life to raising her grandson and cultivating his gifts as child prophet. She finds an unlikely ally when Lovey agrees to foster the boy, Josiah, and his ministry. A child preacher, he attracts a small but dedicated following. Lovey supports his ministry, helping to build a community of faithful, until the interference of outsiders threatens the existence of the community of Zion, and the life of Josiah himself.