Surrounded by hills and pasturelands, the town of Dry Falls is a thriving agricultural community. The town itself and St. Anthony's, the local church, are deeply rooted in the natural order - blissfully ordinary and uneventful. But suddenly life in Dry Falls begins to go awry. A heat wave spikes in March; a three-month drought blights farms and gardens; animals give birth to monsters; women complain of sexual persecution. As one uncanny incident follows another, the natural order is disrupted.

The townspeople seem to be living under a glass bell: the conditions in Dry Falls extend only as far as its borders - over the town line the weather is seasonable and crops ripen on schedule. In one-third of the households in town, men have lost sexual desire and the women blame them. Henry Lieber is the rector of St. Anthony's. He is an arch-believer, but his faith in the Christian God is wavering. He seeks proof of the spiritual dimension in any form, and will take it as he finds it.

Evidence of the mysterious evil grows. An outline of the incubus experience gradually emerges. Although the attacker of the townswomen is invisible, every victim refers to it as "he." And it is clear to Henry Lieber, the self-appointed chief investigator, that the Dry Falls invader is both one and many. It takes the shape of traditional entities - an incubus demon, a succubus, a Frankenstein monster, an extraterrestrial, the Blessed Virgin.

Its complex and absurd intelligence can masquerade as every kind of supernatural phenomenon. What kind of interaction does it want? Why is Dry Falls the target of demonic infestation? How can Henry Lieber, with his limited Christian magic, prevail against it? There is one thing the townspeople of Dry Falls can be certain of: if one invasion is repelled, another will follow...