The action primarily follows Guy Carson and Susana Cabeza de Vaca, two researchers employed by the corporation GeneDyne and stationed at the Mount Dragon facility in New Mexico.

With the help of his feisty lab assistant, Susanna Cabeza de Vaca, Carson begins to unlock the mysteries of the spontaneously mutating influenza virus, dubbed “X-FLU”.

Attempting to alert officials before PurBlood can be introduced across the nation, resulting in an epidemic, Carson and DeVaca set off on horseback across the arid New Mexico desert, hundreds of miles from the nearest civilization.

They are chased by the security director, an eccentric Englishman named Nye whose PurBlood-induced madness has led him to believe that there is a treasure buried in the desert and that Carson and DeVaca are trying to steal it from him.

Aside from the action-ridden plot of Carson and DeVaca, the novel highlights political and scientific battle between the CEO of GeneDyne, Brent Scopes, and his former best friend, Charles Levine, over the ethics of genetic modification.