!"

It was at that moment that Roy, just emerging from the woods, heard Lieut.
Bradbury's angry challenge:

"Prescott, you young scoundrel, I'll get you yet!"

CHAPTER XV.

WHAT MORTLAKE DID.

"Look here," cried Roy, indignantly wiggling in the officer's strong
grasp, "can't you see that this is all a mistake? If you hadn't grabbed
me, I could have caught that impostor."

A great light seemed to break on Lieut. Bradbury.

"Why, bless my soul," he exclaimed, "that's so. I can see it all, now.
That chap who got away wore a gray suit, while yours is a blue serge,
isn't it?"

"It was, before I was thrown into that cellar," said Roy ruefully.

The moon was shining brightly now, and he saw that, in the semi-darkness,
it would have been easy to mistake his blue serge, dust-covered as it was,
for one of gray material.

"Tell me exactly what has happened," urged the officer. "I must confess I
am in a mental whirl over to-night's happenings."

Roy rapidly sketched the events leading up to his capture and
imprisonment, not forgetting to lay the blame on himself for being so
gullible as to be led into such a pitfall.

"Not a word more of self-blame, my boy," cried the young officer warmly.
"Older persons than you would have stumbled into such an artfully prepared
snare, baited as it was with the hope of catching Mortlake in a plot to
destroy your aeroplane. But now I'm going to tell you my experiences, and
we can see if they dovetail at any point."

But when Lieut. Bradbury concluded his narrative, they were still at sea
as to the main instigator of the plot. Of course, the finger of suspicion
pointed pretty plainly to Mortlake, but the rascal had covered his tracks
so cleverly that neither Roy nor the young officer felt prepared to
actually accuse him.

"But I can't see how an ordinary workman would have had either the brains
or the motive to direct such an ingenious scheme to discredit me in your
eyes," concluded Roy, as they finished discussing this phase of the
question.

"Nor I. But hark! Somebody's shouting. It must be Mortlake. Yes, it is.
Hull--o--a!"

"Hullo--a!" came back out of the night.

"Come, we will retrace our steps to the auto and meet him there," said the
lieutenant.

"I wonder if he'll have the face to brazen it out?" thought Roy, by which
it will be seen that his mind was pretty well made up as to the "power
behind" the night's work.

"Couldn't come near the fellow," puffed Mor