On May 31, 1889, the unthinkable happened. The dam supporting an artificial lake at the South Fork Fishing and Hunting Club, playground to wealthy and powerful financiers Andrew Carnegie, Henry Clay Frick, and Andrew Mellon, collapsed. It was one of the greatest disasters in post-Civil War America. Some 2,200 lives were lost in the Johnstown, Pennsylvania, flood. In the shadow of the Johnstown dam live Frank and Julia Fallon, devastated by the loss of two children; their surviving son, Daniel, a passionate opponent of industrial greed; Grace McIntyre, a newcomer with a secret; and Nora Talbot, a lawyer's daughter, who is both bound to and excluded from the club's society. As Frank and Julia, seemingly incapable of repairing their marriage, look to Grace for solace and friendship, Daniel finds himself inexplicably drawn to Nora, daughter of a wealthy family from Pittsburgh. James, Nora's father, struggles with his conscience after bending the law to file the club's charter and becomes increasingly concerned about the safety of the dam. Meanwhile, Andrew Carnegie, Henry Clay Frick, and Andrew Mellon maneuver to establish themselves as the preeminent financiers of the day, solidifying their alliances through their membership in an elite club in the Allegheny Mountains. At the center of these interwoven stories is an artificial lake, the centerpiece of the South Fork Fishing and Hunting Club, and the dam itself -- an emblem of careless self-interest and the devastating consequences it sows.