The book "Boys on Colorado River Motorboats; or, Clues in Stones" by Harry Gordon tells the exciting adventures of three friends - Tom, Jack and Ned, who go on a trip down the Colorado River in their motorboats. During their journey, the boys come across a mysterious footprint in the stone that leads them to an exciting revelation. They will face danger by solving a mystery that will put their lives in danger. Will they be able to solve the riddle in time and avoid the dangers? This book is full of adventure, mystery and friendship, which will turn reading into an exciting journey through the waves of river waters.