In the early 1980s, unexplainable tragedy strikes the family of a young girl. Hours later, the same unexplainable tragedy strikes the family of a young man. One by one, seven people fall victim to an invisible killer and a nation is plunged into terror as officials race to identify the source of a deadly toxin. Finding the source of the toxin actually leads to far more questions than answers in a case that has baffled investigators for nearly three decades.