"I think there are," whispered Dick, after a moment in which he peered through the darkness. Dick had one unusual gift. He had almost a savage's ability to see in the dark, although in daylight his sight was by no means out of the ordinary.
"Look!" he said, again, suddenly. "Up on top of the tower! There is something going up there—it's outlined against that white cloud!"
Harry followed with his eyes and Dick was right. A long, thin pole was rising, even as they looked on. Figures showed on the roof of the tower. They were busy about the pole. It seemed to grow longer as they watched. Then, suddenly, the dangling wires they had first noticed were drawn taut, and they saw a cross-piece on the long pole. And then, with a sudden rush of memory, Harry understood.
"Oh! We have struck it!" he said. "I remember now—a portable, collapsible wireless installation! I've wondered how they could use wireless, knowing that someone would be sure to pick up the signals and that the plant would be run down. But they have those poles made in sections—they could hide the whole thing. It takes very little time to set them up. This is simply a bigger copy of what they use in the field. We've got to get out!"
He looked at his watch.
"Carefully, now," he said. "We've just about got time. That sentry must be just about passing the place where we got over the wall now. By the time we get there he'll be gone, and we can slip out. We've got everything we came for, not that we've seen that!"
They started on the return journey through the woods. More than ever there seemed to be danger about them. And suddenly it reached out and gripped them—gripped Harry, at least. As he took a step his foot sank through the ground, as it seemed. The next moment he had all he could do to suppress a cry of agony as a trap closed about his ankle, wrenching it, and throwing him down.
"Go on!" he said to Dick, suppressing his pain by a great effort.
"I won't leave you!" said Dick. "I-"
"Obey orders! Don't you see you've go to go? You've got to tell them about the wireless—and about where I am! Or else how am I to get away? Perhaps if you come back quickly with help they won't find me until you come! Hurry—hurry!"