For purposes of his own, which a boss did not need to explain, he had nailed boards together to form something like a door, six feet square.  The thing had been leaning against the dynamite shed for some days.

Quite casually, Mr. Wagg went and lifted away this square of boarding, holding to the traverse braces on which the boards were nailed.  He trudged along, carrying it, and came to where Vaniman was standing, observing and wondering.

“Scooch!” snapped Wagg.  “Walk along.  Don’t show yourself past this shield!”

It was a true shield.  Wagg carried it straight up and down.  Vaniman obeyed instantly.  He had a mental flash that Wagg did know exactly what he was about in his tactics.  Lacking all idea of the scheme, Vaniman had not the heart to begin to ask for any details of the big plan at the crucial moment.  He allowed himself to be an automaton.  It was easy to do one thing at a time, as Wagg commanded; knowing nothing about what Wagg intended to do.  Vaniman was not in a position to delay matters by doubts as to the best way of doing the thing.  He walked behind the board screen, conscious that his movements were hidden from the men in the guardroom and, for that matter, from the eyes of anybody in the prison building.

After a walk of a few rods Vaniman found himself close to a big chimney; it served a shop which had been unused since the crew had been at work on the job of filling the pit.  Wagg set down the shield on its edge, as if needing to rest for a moment.

“Open that chimney door and dodge in.  Pull the door to behind you.”

At the base of the chimney Vaniman beheld the iron door provided for the convenience of cleaners and repair men.  The padlock of the door was unhooked.  He lifted the door from its latch, crawled into the chimney, and pulled the door shut.  A moment later, waiting in the stifling darkness, he heard the rattle of metal against metal and the snap of the padlock.  There was the tramp of departing feet.  Gradually he became able to see about him in some degree.  Away up above him was a square of sunlit sky at the top of the shaft.  He saw in one corner a large pail with a cover; inside it were several bottles.  Also, there was a bundle of clothing.

Judging from the amount of food, it was rather evident that Mr. Wagg expected prison-bird Two-Seven-Nine to play chimney swallow for some little time!

Wagg had made a quick job of locking in Vaniman.  The guard tipped the upper edge of the shield inward till it rested against the chimney.  He reached around the end of the boarding and snapped the padlock.  Then he lifted his burden and went on.

About that time a lazy man in the guardroom rolled slow gaze upon the yard.  He saw Wagg moving with the burden and watched until Wagg laid it down flat on the ground.  He opined that it was a part of the bomb-proof shelter that Wagg proposed to build in order to watch the hillock-smashing at close range.  The other guard confirmed that opinion, having information straight from Wagg, himself.