In 1889, one of the worst environmental disasters to befall the United States occurred in Johnstown, Pennsylvania. More than 2,200 people died when a poorly maintained sporting dam gave way and destroyed the town. Only minutes before the catastrophe, a nineteen-year-old girl enters a church in Johnstown, puts a letter into a bottle, and places it inside a safe. In the year 2009, that safe is unearthed. The letter reveals that the author knew of...