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, who begin to die.

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 African-American population? As 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 race war.