A gripping narrative history of the 1889 Johnstown Flood - the deadliest flood in US history - from New York Times best-selling author, NBC host, and legendary weather authority Al Roker.

May 1889: After a deluge of rainfall - nearly a foot in less than 24 hours - swelled the Little Conemaugh River, panicked engineers watched helplessly as swiftly rising waters threatened to breach the South Fork Dam in central Pennsylvania. Though they telegraphed neighboring towns on this last morning in May, warning of the impending danger, residents, used to false alarms, remained in their homes.

At 3:10 p.m., the dam gave way, releasing 20 million tons of water. Gathering speed as it flowed southwest, the deluge wiped out entire towns in its path and picked up debris - trees, houses, animals - before reaching Johnstown, 14 miles downstream. Traveling 40 miles an hour, with swells as high as 60 feet, the deadly floodwaters razed the mill town - home to 20,000 people - in minutes. The Great Flood, as it would come to be called, remains the deadliest in US history, killing more than 2,200 people and causing $17 million in damage.

Al Roker tells the riveting story of this tragedy, which remains one of the worst weather-related disasters in American history. Ruthless Tide follows a compelling cast of characters whose fates converged because of that tragic day, including John Parke, the engineer whose heroic efforts failed to save the dam; Henry Clay Frick, the robber baron whose fancy sport-fishing resort was responsible for modifications that weakened the structure; and Clara Barton, the founder of the American Red Cross, who spent five months in Johnstown leading one of the first organized disaster relief efforts. Weaving together their stories and those of many ordinary citizens whose lives were forever altered by the event, Roker creates a classic account of our natural world at its most terrifying.