 In 1869, the United States begins a railroad mail service to the West Coast which proves highly tempting to train robbers, in particular an organized gang with one of the mail s supposed guardians in their pay. Prizefighter Steve Davis, a former army intelligence man, is hired to track down the gang and save the Territorial Mail Service. Steve goes undercover in territorial prison, leans Morse Code from a fellow prisoner, breaks jail, infiltrates the gang...and finds time to romance dance-hall singer Mary, who proves to have hidden depths...