Chicago, 1982: At least seven people die after taking Tylenol capsules laced with cyanide, sparking a nationwide panic and one of the largest criminal investigations in U.S. history. Is a single mastermind behind these horrific deaths, or merely a convenient scapegoat in a dark conspiracy and possible cover-up? The series reopens the case that turned the world’s best-selling medication into a terrifying icon—and forever changed the way we view the products in our own medicine cabinets.