Robert Livingston, Ray Corrigan, Max Terhune, Mary Russell, Roger Williams, Fern Emmett, C. Montague Shaw, Yakima Canutt, John Ward, George Godfrey, Earle Ross, Frank Ellis, Chief Thundercloud, John Van Pelt
When Professor Marsh disappears while searching for the lost city of Lukachukai, his daughter enlists the help of the Three Mesquiteers.