On May 24, 1869 a one-armed Civil War veteran, John Wesley Powell and a ragtag band of nine mountain men embarked on the last great quest in the American West. The Grand Canyon, not explored before, was as mysterious as Atlantis--and as perilous. The ten men set out from Green River Station, Wyoming Territory down the Colorado in four wooden rowboats. Ninety-nine days later, six half-starved wretches came ashore near Callville, Arizona.

Lewis and Clark opened the West in 1803, six decades later Powell and his scruffy band aimed to resolve the West's last mystery. A brilliant narrative, a thrilling journey, a cast of memorable heroes--all these mark Down the Great Unknown, the true story of the last epic adventure on American soil.