Alex Morales, a young geneticist working for a Florida senator, investigates a mysterious phenomenon in the mountains of Peru: indigenous people who chew coca-leaf experience an unpleasant sensation in the throat, which they call the Burn. Back in Miami, the phenomenon appears among cocaine addicts, leading in isolated cases to death. One of the dead is a hooker, and Alex persuades her friend, Faymi Alonso, to assemble a group of cocaine users for testing. He finds signs of a viral infection among those suffering from the Burn. But before he can act, cocaine is planted in his car, and he is arrested.

He is broken out of jail by a Colombian drug lord, who wants him to work on a vaccine for the burn virus. Alex hides out with Faymi, and makes contact with colleagues who can support his research. A friend at MIT confirms that the virus is man-made and Alex concludes that American drug-war agencies are using it as a weapon in the drug-war, and might have been responsible for creating it. He sets out to entrap the Commissioner of the DEC, Greg Halder, using Faymi as bait. Halder reluctantly agrees to investigate. Suspicion falls on a lab in Houston, run by a Mexican. Alex flies to Houston, but Greg is detained in Washington. In desperation, Alex seeks help from the drug lord who broke him out of jail.

Alex and the drug lord’s men kidnap the Houston lab director, and get the name of the Mexican who has created the virus, a wealthy patriot who is trying to rescue Mexico from the horrific violence of the cartels. Alex tracks him to an archeological site in Guatemala, chases him aboard a local bus, and is able to shoot him down before he can release a more infectious form of the virus. The worldwide spread of the Burn has been contained.