It was inconceivable that America should ever bow beneath the heel of the invading tyrant, the self-styled Emperor Rudolph I-yet two-thirds of the nation had been seized and laid waste. A courageous but deluded people had muttered, "It can't happen here!"-even when the purple hordes had swept over Europe and Asia. Now these people were retreating before the bloody battalions of the conqueror. And finally, when even the women of the nation had hurled themselves against the enemy in a last desperate effort to stay his irresistible progress, America staggered under the most paralyzing blow of all-the devastating barrage of the cholera bombs... What could one man-even though he be the veteran Jimmy Christopher, Operator 5-do against such odds?