Selah is a young girl born into an alternative religion known as the Flock. The members of the Flock – all women and female children – live in a rural compound, and are led by one man, known only as the Shepherd. Selah, who is on the cusp of teenage-hood, is an incredibly devoted follower, but begins to bond with Sarah, an outcast wife who has grown skeptical of the Shepherd's teachings. Selah is given the great honor of participating in the sacred ritual of the birthing of the lambs –upon which they depend for survival– where she has a shocking and transformative experience. She begins to have strange visions that make her question her own reality, and everything the Shepherd has taught her and her sisters.