Dr. Joshua Crandall is in moral crisis. His wife Theo has been an invalid for years, the victim of kidney failure, and although he's resisting every step of the way out of respect for his religious beliefs, he's strangely attracted to a colleague, the mysterious Kristen. He is haunted by wanting to end Theo's suffering; it would be so easy for him, as a doctor, and after all, it is being done all the time in this morally confused world. But deep down he's troubled that he's deceiving himself into believing that his true motive could conceivably be characterized as altruism.
Adding to his moral crisis is his long campaign to end the heinous practice of illegal organ harvesting. His outrage intensifies when he learns through his sister Jessica, a spunky FBI agent spearheading the re-opening of cold cases surrounding organ theft, that Theo herself as a young adult was the victim of such a crime. He further discovers that his putative mistress Kristen is the recipient of a stolen kidney. The thought creeps into his mind that this simply cannot be a coincidence, and although he dismisses it as preposterous, the idea keeps returning, seemingly of its own volition. Can it be that Theo and Kristen are somehow linked?
Kristen begins to exhibit some very unusual behavior. Just who or what is she? To satisfy his outrage over the corruption in the organ transplant business, Josh has made himself into an avenging angel on a mission of justice. But as Josh's conviction grows that Kristen is indeed more than she seems, his crusade transforms from satisfying his sinful obsession with revenge, into a quest for renewal and awakening.
The story wraps most excitingly and satisfactorily, with the evildoers appropriately identified and punished, Josh dodging his temptations and accepting the second chance in life arranged for him by higher powers, and Kristen revealing her true nature.