Which was not, Barney felt, too reassuring. He looked back. The door through which they had come was the one by which they had left. But beyond it now lay a section of the entrance hall of the Sweetwater Beach house.
"Don't let that fool you," said McAllen, following his gaze. "If you tried to go out into the hall at the moment, you'd find yourself right back in the cabin. Light rays passing through the Tube can be shunted off and on." He went over to the door, closed and locked it, dropping the key in his pocket. "I keep it locked. I don't often have visitors, but if I had one while the door was open it could be embarrassing."
"What about the other end?" Barney asked. "The door appeared in the cabin when you turned those switches. What happens now? Suppose someone breaks into the cabin and starts prowling around—is the door still there?"
McAllen shook his head. "Not unless that someone happened to break in within the next half-minute." He considered. "Let's put it this way. The Tube's permanently centered on its two exit points, but the effect ordinarily is dissipated over half a mile of the neighborhood at the other end. For practical purposes there is no useful effect. When I'm going to go through, I bring the exit end down to a focus point ... does that make sense? Very well. It remains focused for around sixty or ninety seconds, depending on how I set it; then it expands again." He nodded at the locked door. "In the cabin, that's disappeared by now. Walk through the space where it's been, and you'll notice nothing unusual. Clear?"
Barney hesitated. "And if that door were still open here, and somebody attempted to step through after the exit end had expanded—"
"Well," McAllen said, moving over to a wall buzzer and pressing it, "that's what I meant when I said it could be embarrassing. He'd get expanded too—disastrously. Could you use a drink, Mr. Chard? I know I want one."
The drinks, served by Fredericks, were based on a rather rough grade of bourbon, but Barney welcomed them. There was an almost sick fascination in what was a certainty now: he was going to get the Tube. That tremendous device was his for the taking. He was well inside McAllen's guard; only carelessness could arouse the old man's suspicions again, and Barney was not going to be careless. No need to hurry anything. He would play the reserved role he had selected for himself, leave developments up to the fact that McAllen had carried the burden of his secret for twelve years, with no more satisfactory confidant than Fredericks to trust with it. Having told Barney so much, McAllen wanted to tell more. He would have needed very little encouragement to go on talking about it now.
Barney offered no encouragement. Instead, he gave McAllen a cautiously worded reminder that it was not inconceivable they had an audience here, at which McAllen reluctantly subsided. There was, however, one fairly important question Barney still wanted answered today. The nature of the answer would tell him the manner in which McAllen should now be handled.
He waited until he was on his feet and ready to leave before presenting it. McAllen's plump cheeks were flushed from the two highballs he had put away; in somewhat awkward phrases he had been expressing his gratitude for Barney's generous help, and his relief that because of it the work on the Tube now could be brought to an end.