 An outlaw known as the White Mask is robbing the silver shipments from Don Sebastian s mine and Larry Prescott has been called in. Larry soon suspects the Don s foreman Douglas who stands to gain if the shipments don t get through. So he sends out a fake pack train planning to get the White Mask when he attacks. But Douglas learns of the hoax, puts on his white mask and he and his men go after the real silver shipment.