They knew that must remain forever a secret from them.
There was a sudden stir among the Three. Jeter and Eyer turned aside for a moment to peer down upon New York City. They held their breath with horror as they saw the smoking devastation which must have buried thousands of people. The wrecking had been all but complete. Only the finest buildings still stood. Jeter wondered why the falling back of the shattered buildings had not shaken down those which the Sitsumi crowd had not wished to destroy. The repeated shocks must almost have shaken Manhattan Island on its foundations.
They saw what had caused the sudden stiffening of the Three. Sitsumi, busily engaged at something else nearby, quietly approached the Three.
"What is it?" he asked.
"Rescue planes," said Wang Li. "New York City sends six fliers to rescue Jeter and Eyer. New planes. They'll reach us, Sitsumi. We should have thought to destroy all dangerous air ports. A fatal oversight!"
Sitsumi's eyes were grave. He looked at each of the Three in turn.
"God!" said Jeter's whispering lips. "If we could read their minds! If only we could guess what it is they fear, we'd have the secret by which we might destroy them."
"They're vulnerable," said Eyer, "but how?"
"Watch!" said Jeter. "Listen! And here's to those six unknowns coming up to, maybe, get the same dose we're due for! We were closely watched. New York City knows exactly where we vanished in the sky. Those six planes are aiming at us—at a spot in the stratosphere they can't see. And yet, why should Sitsumi and the Three be so fearful? All they have to do is move a half mile in any direction and they'll never find them."
"But to move will interfere with their plans," said Eyer. "Lucian, look at the expressions on their faces! Something tells me they are vulnerable in ways we haven't guessed at. If we knew the secret maybe we could destroy them. We've got to discover their weak spot."