The blank metal face on the grandfather clock swung back to reveal a group of four dials, each graduated in a different manner, only one of them immediately familiar. Barney studied the other three for some seconds, then their meaning suddenly came clear. The big clock had just finished softly talking away the fourth hour of the first day of the first month of Year One. There were five figures on the Year Dial.

He stared at it. A five-year period of—something seemed to be the key to the entire setup.

Barney shook his head. Key it might be, but not one he could read without additional data. He snapped the cover disk shut on the unpleasantly suggestive dials, and began to go mentally over McAllen\'s letter.

The business that in twenty-four hours—twenty now—the manner of leaving the cabin would become "apparent" to him—that seemed to dispose of the possibility of being buried underground here. McAllen would hardly have provided him with a personal model of the Tube; he must be speaking of an ordinary door opening on the immediate environment, equipped with a time lock.

In that case, where was the door?

Barney made a second, far more careful search. Three hours later, he concluded it. He\'d still found no trace of an exit. But the paneling in any of the rooms might slide aside to reveal one at the indicated time, or a section of the floor might swing back above a trap door. There was no point in attempting to press the search any further. After all, he only had to wait.

On the side, he\'d made other discoveries. After opening a number of crates in the ............