In a New Jersey suburb, two women die of brain aneurysms within twenty-four hours—events that cause the government to suspect that a terrorist cell has unleashed a deadly biochemical agent. With each glass of water they drink, the people of Trinity Falls are poisoning themselves. A world away in Pakistan, a sixteen-year-old computer genius working as a virtual spy for the United States sees an influx of chatter from extremists about a substance they call Red Vinegar that will lead to many deaths in Colony One. Can he warn the victims before it's too late? A Printz Honor Award winner and two-time Edgar Allan Poe Award finalist, Carol Plum-Ucci explores disturbing new terrain in this riveting novel that examines the heroes and victims involved in a terrifying act of bioterrorism.

ShadowStrike poisoned the water of Trinity Falls two months ago. Now the Trinity Four, the teens most affected by the poison, have been isolated in a remote mansion under twenty-four-hour medical care while scientists on four continents rush to discover a cure. Meanwhile, U.S. operatives scour the world for the bioterrorists responsible for this heinous crime, as two teen virtual spies, also infected, hunt for the criminals on the Internet. The danger remains real—for ShadowStrike has every reason to pursue the Trinity Four, and their evil plan will unleash a new designer virus that’s even deadlier than the first.