Pauline Haddon

Schmidt is the head of a group of spies building an arsenal along the border. Tim from the American side and Gringo from the Mexican side have been sent to investigate. But when they arrive they find the men they were to meet murdered and themselves arrested for the murders. (imdb)

Disguised as a gambler, U.S. Marshal Tim Donovan Tim McCoy) rides the Black Mountain Stage which is held up by Pete Smith (Ted Adams) and his gang. Tim and his pal, Tombstone (Ralph Peters) pursue --- no, not on foot as their horses were tied to the stage --- and find the robbers trying to open the strongbox. The outlaws flee and Sheriff Clay Matthews (Rex Lease) arrives and arrests Tim and Tombstone as the robbers. Judge Harper (Frank LaRue), also a passenger, frees Tim and Tombstone.