A nonhuman life form run amok energizes Ouellette's compulsively readable second thriller just as it did his first, The Deus Machine. Only here the threat is viral, not virtual. Scientist Elaine Wilkes of the Webster Foundation has used a computer simulation to predict that, within 10 years, a mutated form of the common Chlamydia psittaci virus will decimate the world's human population. The money people behind Elaine's research want to use this information to create a vaccine they can market after a few million people die. But, in the first of the novel's many coincidences, the mutated virus already exists. As Elaine enlists the aid of Seattle detective Philip Paris and public-health official David Muldane, the virus is poised to sweep from Africa to the rest of the world. The images Ouellette uses to describe viruses?tribes, explorers, colonists, merchants?are vivid and effective, and he lays out the complicated chain of events that created the killer disease clearly and succinctly. He stretches credulity, however, by making one of the links in that chain not only a Webster Foundation employee but one of Elaine's co-workers. Such contrivances mar a thriller that is otherwise excellent. Ouellette does an outstanding job of creating a world in which the potential outbreak of disease terrifies nearly everyone, from a twisted serial killer whose weapon of choice is E. Coli bacteria to a jailed gangster concerned about TB. Before they finish this gripping tale, readers, too, will have become compulsive hand-washers.

Huge Uni Corp. has more than its share of greedy, power-hungry officers and employees. It sets out to parlay its EpiSim cytoputer system into tremendous profits by first designing an antibiotic and then withholding it until a pandemic kills off enough people to raise the drug's price exorbitantly. Elaine Wilks, one of the company's good guys, does the epidemiologic work until she begins to smell not a rat but a chlamydia-infected parrot. After the disease germs break out of the research labs, they hit a small island off Africa, then spread rapidly throughout the world, creating the third pandemic (after those of Justinian and the Black Death) of the title. Helped along by Barney Cox, one of the most disagreeable thugs in recent pop literature, civilization begins to unravel. The good guys--newly widowed police detective Philip Paris chief among them--finally win, and pleased readers will be watching for Ouellette's third novel. William Beatty