Homicide detective Catherine Palmer pursues a sexually deviant serial killer. The mysterious and seductive Vickie Kittrie reveals that each victim belonged to an elite club of beautiful, prominent, and sexually experimental women. To catch the killer, Catherine must trust Vickie to guide her through this dangerous erotic underground in which no desire is forbidden and no one is who she seems. At the heart of this deadly mystery is psychotherapist Dominick Broussard, who knows every uncontrollable impulse of his patients and harbors secrets of his own. Mercy is a highly-charged thriller that seduces the audience into the most intimate relationship of all -- between killer and victim.