Central Pennsylvania, May 31, 1889: After a deluge of rain swelled the Little Conemaugh River, panicked engineers watched helplessly as swiftly rising waters threatened to breach the South Fork dam. At 3:10pm the dam gave way, releasing 20 million tons of water. The deluge wiped out nearly everything in its path before reaching Johnstown, a vibrant steel town 14 miles downstream. Traveling 40 miles an hour, the deadly floodwaters razed the mill town in minutes. The Great Flood remains the deadliest in US history, killing more than 2,200 people and causing $17 million in damage. In RUTHLESS TIDE, Al Roker follows an unforgettable cast of characters whose fates converged because of that tragic day.