ever quite
so sleepy in my life!"

"Now, on the way back," Will cautioned, "we ought to keep still and keep
a sharp lookout for the person who was sneaking around our quarters."

"Whoever it was may be between us and the shaft," George suggested.

"If I thought so," Will argued, "I'd just stand around and wait until
they pass us on the way in. I don't want to find those boys just now.
There's a mystery connected with this mine which the caretaker knows
nothing about, and which Mr. Horton never referred to when he sent us
down here.

"We wouldn't be able to breathe if we didn't discover an air of mystery
every fifteen minutes," George declared.

Half way back to the shaft, the boys, who were walking very softly in
their stockinged feet, heard a rattle as of a moving stone or piece of
coal in the passage, and at once drew up against the side wall.

While they stood there, scarcely daring to breathe, they sensed that
some one was passing them in the darkness. The tread was light and
brisk, and they thought they heard a soft chuckle as the unseen figure
breezed by them.

"I'll bet the lad who was listening near our door never came down the
shaft until after we did!" George whispered after the figure had passed
by.

"That's very likely!" agreed Will.

"Then he may have been poking around our quarters while we have been
gone."

"That's very likely, too."

Believing the way to be clear now, the boys hastened on toward the
shaft. Just as they reached the foot of the ladder they heard a sound
which sent the blood throbbing to their cheeks.

"He's making fun of us!" exclaimed George.

"It looks like it," admitted Will.

The sound they heard was the low, complaining snarl of the Wolf.

"The nerve of him!" exclaimed George.

"Perhaps he'll answer now!" Will suggested.

Then followed the "slap, slap, slap!" of the Beaver Patrol.

No answer came from the darkness beyond the shaft.

"He's got his nerve with him!" declared Will. "When I get hold of him,
I'll teach him to answer Boy Scout challenges!"

When the boys got back to their quarters they found Tommy and Sandy
sitting in the darkness with their automatics and their searchlights in
their hands. One of them turned on a finger of light as the boys entered
but immediately shut it off again.

"What's coming off here?" demanded Will.

"Do you know what those fellows did?" asked Tommy. "They came here while
we were asleep and stole about half our provision