Mr. Johnson made no reply, and a few minutes later, the three men walked away. No sooner had they disappeared up the lake than Penny and Salt came out of hiding from among the trees.
“You have to hand it to Professor Bettenridge,” commented the photographer with grudging praise. “He’s a smooth talker. I’ll bet a frosted cookie the test could be held at one time as well as another so far as the village authorities are concerned. He has a special reason for wanting it at nine o’clock.”
“Probably to give Webb time enough to work on the mine or exchange them,” Penny said, and then frowned thoughtfully. “But what if the machine actually should work? After all, the professor agreed to explode Mr. Johnson’s mine, and apparently he’s marked it with his initials. It won’t be easy to substitute another one now.”
“All the same, if I’m any good at guessing, it will be done. Now what shall we do until nine o’clock? Grab ourselves something to eat?”
Penny was about to suggest that they drive to a village cafe, when she noticed Webb returning alone from up the beach. Barely did the pair have time to duck out of sight behind a boulder before he approached.
Walking directly to the shack, he unlocked the door, and entered.
“Now this must be where the hocus-pocus begins!” Salt whispered. “We’ve got to find out what he does to that mine.”
“Louise and I climbed up in that tree the other day and looked through the glass in the top.”
“Then that’s the trick for us! Come on!”
Making no sound, the pair climbed the tree close beside the shack. Noiselessly, they inched their way toward the skylight, and lying flat, peered down into the dark interior.