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
Frank Marshall
Marguerite Churchill
Nancy Foster
Crawford Weaver
Slim Hewitt
Ward Bond
Don Foster
Charles Cahill Wilson
Colonel McCollum (as Charles Wilson)
John Hamilton
Cummings
Arthur Loft
Gardner
Nick Copeland
Lefty (as Nicholas Copeland)
John Tyrrell
Feeney (as John Tyrell)
