The Riders of the Whistling Skull

When Professor Marsh disappears while searching for the lost city of Lukachukai, his daughter enlists the help of the Three Mesquiteers.

• Director: Mack V. Wright
• Cast: Robert Livingston, Ray Corrigan, Max Terhune, Mary Russell, Roger Williams, Fern Emmett, C. Montague Shaw, Yakima Canutt