In Las Vegas, rookie EPA investigator Evangeline Bixby searches for her uncle, who went missing while seeking the source of a mysterious biological toxin. Retired cop Danforth encounters a man outside the downtown casinos who seems to rot to death before his eyes. Danforth's former partner, Chuck Needles, recalls a series of unsolved deaths involving an unknown toxic agent. Underneath the bright surface of Vegas, a darkness grows, savage, monstrous and ravenous. Bixby, Danforth and Needles will risk it all to stem a poisonous tide of murder and destruction hatching beneath Sin City.