The Shadow remembered this submarine room. Once he had rescued his agent, Harry Vincent, from imprisonment within these very walls. Deep beneath the house, this room was below the level of the lake. It fronted on a subterranean channel under the island.
Professor Whitburn had used it for torpedo tests. At the time of Harry Vincent’s imprisonment, the torpedo tubes had been in use. A girl — Arlette Deland — had been a prisoner with Harry; and the agent, at The Shadow’s command, had sped the girl to safety within a torpedo.
But none of these contrivances were usable at present. Machinery dismantled, torpedoes gone, the room was but a relic of Whitburn’s former experiments. Just above the machine on which Quex rested was a periscope that formed a solid shaft up through the top of the room. This led above ground, and the professor had used it to watch the progress of his torpedoes.
At the time of Harry’s imprisonment, there had been water sluices in the submarine chamber. These had been installed in order to flood the room in case spies tried to enter. No longer needed, the sluices had been blocked.
But the locked door still remained. The Shadow had opened it once from the outside. The inner wall, however, offered a most difficult task — one that would take hours, at least. By morning — before the barrier could be cut — life could no longer exist in this cramped space. Moreover, Bragg, returning and departing, would be on the way to Eric Hildrow’s toils.
Yet The Shadow approached the door. He studied its smooth, riveted surface. He saw that with few tools available, this means of exit afforded slow progress. With him, The Shadow had another means of attacking the door. Two powders, mixed, would form a high explosive that might blast the barrier from its hinges.
Here, again, was danger. The steel door was unusually formidable. Should a first blast fail, as was highly probable, the fumes would exhaust the remaining air supply. That would hasten death instead of prolonging life.
WHILE The Shadow was examining the door, Quex rose from his perch. In placid fashion, the big cat dropped from the machine and stalked over to the stone steps. Ascending, Quex began to claw at the fringe of The Shadow’s cloak.
Lowering his gaze, The Shadow looked at the cat. Quex moved to the door and showed the claws of one paw as he scratched inquiringly at the steel barrier. The Shadow laughed softly; then turned toward Professor Whitburn.
“Quex always does that,” explained the white-haired inventor. “If he is locked out at night, he claws at the front door until I open it.”
The cat began to mew.
“That follows,” added the professor. “Then, if no one answers, he sits by the door. He waits until he is admitted. Twice, when I was away all night, I returned to find him waiting for me.”
The Shadow made no response. Yet his steady gaze impelled the professor to a further statement.
“If that fiend had left Quex in the study,” declared Whitburn, “Bragg would have known that something was wrong. When he returns to-morrow, you understand.”
“And if the cat had been taken from the house,” whispered The Shadow, “then—”
“Quex would come back to the front door,” completed Whitburn, “to wait there for the first person who might arrive. If he could only be where Bragg could find him—”
Whitburn shook his head as he speculated. He watched The Shadow come away from the door. He saw the cloaked rescuer stop at the periscope above the machine.
The periscope consisted of a lower reflector, connected with another mirror above the ground. Between the two were lenses. Only the lower reflector was visible; the rest of the apparatus was encased in the tube that led up through the low ceiling of the room.
The Shadow studied the periscope. Whitburn thought that he was trying to sight through it. The professor could see no purpose in such action, for nothing could be gained by staring out into the blackness above ground.
As Whitburn watched, however, he suddenly realized The Shadow’s purpose. The periscope was patterned after those used in undersea boats; its construction, though, was of the most simple sort, for it had no water to encounter. The encasing tube merely protected the apparatus; and it was firmly fixed in position.
That tube had given The Shadow a solution to the problem of failing air. With gloved hands, he began to detach the lower reflector. That done, he worked to remove the lenses and other connections from within the tube itself.
PROFESSOR WHITBURN chortled. The Shadow was forming an air shaft to the clear atmosphere above. Emptied of its equipment, the periscope tube formed a tunnel six inches in diameter, leading straight upward. Only one problem remained. That was the upper reflector.
Sudden dismay gripped Whitburn as he saw The Shadow blink a flashlight up through the tube.
“The upper reflector is encased,” exclaimed the professor. “It is larger than the tube. It is screwed in place. Even if you break its bottom lens, you can not obtain air. There is an outer glass, off at an angle—”
He shook his head as he paused. The Shadow was unscrewing a long bar from the machine beside the old torpedo tube. With it, he could attack the lower lens of the upper reflector; but as Whitburn had said, it would be impossible to curve this bar and reach the outer glass.
The Shadow, however, had another plan. From beneath his cloak, he drew forth an odd device. It was a rubber suction cup — one of those which The Shadow used to scale vertical walls. The rubber disk was just a trifle smaller than the periscope tube.
Laughing softly, The Shadow used a clamp to fit the disk to the end of the steel bar.
He thrust the disked end of the bar straight up the periscope tube. Whitburn could hear the squdge of the rubber sucker as it pressed against the lower lens at the top of the tube. Then he began to revolve the bar. The professor gaped.
The suction cup had gained a grip. By twisting the bar, The Shadow was unscrewing the mushroom cap that covered the upper end of the periscope tube. After a few moments, The Shadow thrust the bar upward. A puff of air came down the shaft.
Jerking at the bar, The Shadow managed to detach the suction cup. Professor Whitburn could hear the loosened cap rattle away from the top of the tube. The submarine chamber was no longer a death trap. The prisoners could remain here indefinitely, with no danger of suffocation.
Yet this passage to the outer air afforded no means of escape. Professor Whitburn wondered what would follow. There would be no chance of communication with Bragg when he came on the morrow. That meant prolonged entombment, with eventual starvation.
THE SHADOW had produced a sheet of paper. On it, he was printing penciled words. A message — but to whom? Whitburn as puzzled; so was Stephen. Then they watched the Shadow wad the message into a small packet which he tied with a short piece of stout cord.
A soft laugh. The Shadow turned and advanced to the steel door. Even then, the watchers did not divine his purpose until they saw him stoop beside the cat that was waiting on the steps. Quex offered no protest as The Shadow attached the message to the top of a thin leather collar that the cat was wearing.
Lifting the docile feline, The Shadow carried Quex to the periscope tube. He lifted the cat and pushed it into the six-inch shaft. Whitburn and Stephen could hear Quex clawing at the smooth inner surface of the tube.
Holding the cat there with one hand, The Shadow reached to the machine and obtained the lever, which still had the suction cup in place. He raised the disked end of the rod and used it to support the cat within the periscope tube. With both hands, he thrust the rod slowly upward.
Quex was riding up on an improvised elevator. The Shadow could hear the cat clawing and shifting about. Then the top of the rod reached the ground level. The rod shook slightly as Quex plopped off the suction disk and landed on solid earth. The Shadow withdrew and removed the rubber cup.