Synopsis by Hans J. Wollstein
Laura (Rosemary La Planche) succeeds in warning Dave (Kirk Alyn) about the booby-trapped box just before it explodes and kills the villainous Professor Williams (Bruce Edwards). Unable to decipher Williams' journal, Laura suggests that Dave contacts Professor Elwood Graves, who, she remembers, used to confer with the kidnapped Professor Clayton regarding Abistahn. Realizing that Professor Graves may reveal her true purpose, Nila (Carol Forman) sends her henchman, Gordon (Roy Barcroft), to intercept the Overland Express carrying the professor. Dave, however, gets suspicious after receiving a telegram from Graves and Laura suggests they meet him en route. Parachuting from a plane piloted by Laura, Dave lands on the railroad tracks right in the path of the speeding express train.