The plot revolves around the loveless marriage of a socially backward couple. The ultra-religious husband is totally over-the-top in his beliefs about love, marriage, sex, and the woman's place in the home. His dowdy wife is left without any love or children from her fundamentalist husband. Their lives are turned completely upside down when a travelling salesman seeks their help with his car troubles and ends up bedding the wife. Caught in the act by the husband, the salesman soons finds himself locked in the basement for the rest of his life unless he can find someway to escape. After years of entrapment, the pitiful salesman becomes more beast than human and the book takes off from there.