FBI Agent Robert Cavanaugh has been transferred from the organized crime unit to the slow-paced field office for southern Maryland, where the "biggest federal crime is the condition of the roads." His main job is to keep tabs on the various fringe groups that inhabit the rural backwoods of Maryland. But things take an unpleasant turn when a nurse at a local hospital notices a sudden increase in the incidence of fatal strokes among otherwise healthy black adults. The trail leads to a new strain of malaria that causes rapid blood clotting in people with sickle-cell trait (which occurs more frequently in blacks and Indians). It's an unlikely natural mutation, yet there's no hard evidence of human intervention. Did a fringe hate group arrange for a bioengineered weapon to decimate the black population? As the disease begins to spread and more people die, Cavanaugh must convince the FBI to look for the answers before it becomes an epidemic that threatens millions of lives ... or even a race war.