In 1827, a cult in Western Illinois sequesters themselves. Shunned for their beliefs in polygamy, they struggle to adapt to their new environment. They've been driven from their colony in Rochester, New York, and they now isolate themselves guarding against the day when others will attack their community.

To ensure the commune's future after years of inbreeding, elders choose the dark-eyed, black-haired Eli Thornman to become the winnower. He uses his imposing frame to his advantage, seeking to intimidate his fellow settlers. His freakish looks complete the image of a man bent on doing evil. As a youth, he was the victim of a horrendous attack on his commune in which he was severely burned, disfigured, and emasculated. Eventually, he becomes a twisted fiend who enjoys his elected duties as winnower of the weak and helpless too much.

With every victim he removes from life, he slips further toward the dark side. Many of his brethren never fully understand the underlying causes of his obsession with killing the infirm in his community. However; in time, they come to know the true horror of his inner being through the fulfillment of his ghastly duties as the winnower.