Thundering across a ravished America comes a loot laden train bearing twenty million dollars in gold, hurtling toward the despoiled metropolis of New York, where the dread foreign conqueror, Emperor Rudolph I, has established headquarters. Suddenly the train trembles to a stop. A desperate little band of American patriots, who refuse to bow to the conqueror's yoke, make a bold attack. Their leader, Jimmy Christopher, known as Operator 5, realizes that with that trainload of gold he can flood the skies with a thousand fighting planes, the only chance for America to repel the brutal invaders! Already they have ravished the Eastern seaboard. Even now they are hammering at the surviving citadel of American freedom-the Rocky Mountain stronghold of the brave men who will not yield.