 To what is the title of the story, “Silence is—Deadly” referring?
SILENCE IS—DEADLY By Bertrand L. Shurtleff Radio is an absolute necessity in modern organization—and particularly in modern naval organization. [Transcriber's Note: This etext was produced from Astounding Science-Fiction April 1942. Extensive research did not uncover any evidence that the U.S. copyright on this publication was renewed.] That would be Nelson, his navigating officer. Androka had arrived on board the Comerford the day before she sailed from Norfolk. With him came a boatload of scientific apparatus and equipment, including a number of things that looked like oxygen tanks, which were now stored in the forward hold. Androka had watched over his treasures with the jealous care of a mother hen, and spent hours daily in the room in the superstructure that had been assigned as his laboratory. Overhead, the sky was a storm-racked mass of clouds, broken in one spot by a tiny patch of starlit blue. It was Nelson, his shaggy blond brows drawn scowlingly down over his pale eyes; his thin face a mass of tense lines; his big hands fumbling at the neck of his slicker. Nevertheless, his taut face, restless, searching eyes, and eternally nervous manner got Curtis' goat. Nelson had no answering smile, although there had been a great deal of good-natured joking aboard the Comerford ever since the navy department had sent the scientist on board the cruiser to carry on his experiments. "I'm not sure about my dead reckoning. This storm—" Curtis threw his arm around Nelson's dripping shoulders. "But this storm, sir!" Nelson avoided Curtis' friendly eyes and slipped out from under his arm. "Not that I've lost confidence in you, Nels, but just because you asked for it!" Nelson's estimate, I'm checking back," he declared, frowning at the two papers and hastily rechecking his own figures. With all these rocks and islets—" "Radio?" repeated the little Czech, thrusting his face between the other two, in his independent fashion that ignored ship's discipline. It will be no more than Hitler can get when Zukor Androka decrees silence over the German airways! Then he hastened to the radio room, with Nelson at his heels, and the Czech trotting along behind. A frightened operator came out, still wearing his earphones, and stood staring upward incredulously at the aërial. "Yet not dead, gentlemen! The waves are what have been upset. I have shattered them around your ship, just as I can eventually shatter them all over Central Europe!
 Androka’s zone of silence is used as a deadly tool against the Comerford’s crew.
 Androka’s zone of silence is used as a deadly tool against the Nazi war effort.  Androka’s zone of silence is used as a deadly tool against the Comerford’s crew.  Androka’s zone of silence is used as a deadly tool, made in the name of revenging the Czech war effort.  Androka’s zone of silence is used as a deadly tool, helping the Americans sneak up on a Nazi Islet.