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.
Bruce Cabot
Marguerite Churchill
Crawford Weaver
Ward Bond
Charles C. Wilson
John Hamilton
Arthur Loft
Nick Copeland
John Tyrrell