An explosives carrier at an oil field falls in love with a colleague's daughter.

Two newly-appointed postal inspectors, Frank Marshall and 'Slim" Hewitt, set out to track down the sender of a time-bomb to a U. S. Senator and, during their investigation, run across a hooded organization that is terrorizing an American city. They also meet Don Foster, who is loud in his condemnation of the terrorists, and his sister, Nancy, who fears for her brother's life.

A young singer, Marge Dexter, becomes involved in trouble when she works in a nightclub in which two of the band-members are in reality undercover-police officers who believe that the club is the headquarters of a dangerous gang of crooks.

Undercover agent Mark Owens is sent to aid the Border Patrol in the trans-border town of Hernandez in breaking up a well-organized band of smugglers.