In the fall of 1982, the Chicago metropolitan area was gripped by fear and uncertainty as a series of mysterious deaths unfolded. Seven people, ranging in age from 12 to 35, died after consuming Tylenol capsules laced with potassium cyanide, a deadly poison. The Chicago Tylenol murders, as they came to be known, remain one of the most infamous unsolved cases in American history. This article explores the timeline of the tragedy, the investigation that followed, the societal and industrial impacts, and the enduring mystery surrounding the perpetrator.