Fertile Flock is the finale of the trilogy that began with Prurient Parishioners and continued with Concupiscent Congregation. The results of undisciplined libido become apparent.
An unforgivable breach of her marriage vows that somehow turns into a long illicit affair with a neighbor down the street. Monica found herself unable to stop, and not just with her neighbor.
This is a story from a work friend, he has told it to me, and so I have presented it as if he were telling you. He found himself submissive to a much older man who then makes him help coerce his wife to sexually submit to him too.