llest
particular.

Scarcely daring to breathe, Rob listened with all his might to the
conversation of the oarsmen.

At the same time the thought was running through his mind that he had
acted rashly in taking the step he had. But the boy pluckily made up
his mind to stick to his resolution of discovering just what was going
on inimical to the plans of the United States Government and Mr. Barr.

Before very long the prow of the boat grated on a sandy beach, and the
two men, gathering up some rolls of paper and several bulky-looking
objects, left the craft, first securing it by an anchor and line.

As their footsteps died away, Rob ventured to raise his head above the
gunwale of the boat and follow them with his eyes. He saw them ascend
the beach and enter the hut, apparently a structure once used by
fishermen or hunters.

After an interval a light shone from the solitary window of the hut, and
Rob came to a sudden resolve to find out just what was going forward.
With this object in view he clambered out of the boat, taking every
precaution against making unnecessary noise. On hands and knees he then
approached the lighted window.

The night was dark, and, standing at a fair distance from the casement,
he did not feel much fear of being seen from within. It is hard for
persons in a brightly lighted chamber to perceive what is going on
outside.

Seated around a rough table in the hut, which consisted of only one
room, Rob saw three men. Two of them, undoubtedly, were those who had
unconsciously rowed him to the island. The other he recognized with a
start as the possessor of the face which had peered through the transom
on the memorable night in Hampton, when plans for the experiments on the
island were in process of being formulated. In other words, the third
member of the party was none other than Nordstrom Berghoff, the spy.

Instantly many things that had been vague to Rob crystallized into a
clear understanding of the situation. The signals from the island, the
indignation of Barton over the presence of the Boy Scouts, and the
stealing of the plans and models, all stood out plainly now as being
part of an elaborate plot of which Berghoff was the mainspring.

A wave of indignation swept over the boy as he contemplated the rascals
within the hut gloating over the things they had obtained from the
treacherous Barton.

"The scoundrels," he thought; "so they think they can rob Uncle Sam of
one of the greatest