 In 1539, Hernando de Soto s Conquistadors landed in Florida in search of new lands and treasure for the Spanish Crown. Three years later, they were run off the continent by Native American warriors that lived on enormous, earthen pyramids along the Mississippi River. Who were these people? And how did they defeat one of the world s most powerful armies? Follow Josh Bernstein as he paddles down the bayous; builds his own earthen pyramid with modern equipment; and scuba-dives the cold, dark waters of Wisconsin to solve the mystery of America s pyramid builders.