Seven people in Chicago died in three days in 1982 after taking Extra Strength Tylenol laced with cyanide. Nobody has ever been charged. Every seal on your medicine bottle comes from this case.

On September 29, 1982, a twelve-year-old girl in Elk Grove Village named Mary Kellerman took a capsule for a sore throat before school. She was dead within hours. By the end of that week, six more people were dead across the Chicago suburbs, including three members of the same family who took capsules from the same bottle on the same afternoon.

It took two off-duty firefighters comparing notes on a phone call to figure out what the deaths had in common. It took a nurse named Helen Jensen going back to a victim's house and counting the capsules to prove it.

In this episode, we walk through all seven victims, the seventy-two hours it took a ...