Tamara Duffy spots her former boyfriend on the steps leading down to a crowded Tokyo subway station. The 29-year-old American follows him into a train packed with morning commuters. Aum Shinrikyo member Siha walks down the steps of the station wearing a surgical mask and gloves, carrying a clear plastic umbrella in one hand and two bags of nerve gas in the other. Inspector Shin Nomura, sitting at his desk at the Tokyo Metropolitan Police Department, knows something bad is about to happen, but is powerless to stop it. It's March 20, 1995, and their lives are about to change forever.