A scientist is murdered and a lab rat escapes when industrial espionage goes awry. But far worse things begin to happen when the lab rat, infected with a newly engineered virus becomes Screed's next meal. Designed to combat HIV, the virus becomes lethal to vampires as it multiplies and intensifies each time they "feed". As the virus spreads rapidly through the vampire community, it infects Vachon, Nick, and LaCroix. Nick races agains time to find the killer - while Natalie struggles to find a cure.