Scripted by Wallace Smith from his own story published in "Hearst's International Cosmopolitain Magazine,", Mexican-bandit Montero and his deaf-mute sidekick, Coloso, are being pursued through the sand-dunes of southern Arizona by lawman "Bob-Cat" Manners and his posse. Montero has intentions of robbing the bank owned by skinflint Lucius Perkins, but is sidetracked by the attractions of singing-teacher Helen Wardell. He learns that Perkins has marital designs on Helen and holds the mortgage on her ranch. But Helen is in love with Bill Howard. Perkins offers Montero money to kill his rival, but Montero fakes the murder. Prepared for a double-cross of his own double-cross, Montero takes the sheriff's posse prisoners, collects the offered blood-money from Perkins, and then forces Perkins, as the local justice-of-the-peace to perform a wedding ceremony for Helen and Howard.