A woman is found in an abandoned house, the victim of cyanide poisoning, which has mottled her skin and turned her blood a dark shade of purple. Detective David Parks, battling his standing within the LAPD, is brought on to solve the murder. Forensic toxicologist Jacqueline Isley joins him to solve what becomes a series of gruesome murders: A famous photographer bleeds to death from his eyes while a woman's own body chokes her to death as it shuts down, organ by organ. Lives are threatened as Det. Parks and Dr. Isley get closer to the truth behind this poisonous killer. But as their feelings for each other intensify, Parks will have to discover just what he's willing to sacrifice and how far he'll go in order to stop a killer whose thirst for justice knows no limits-and whose obsession for vengeance knows no ends.