he noted the arrival of M. Lemaire, alone in a runabout, just about an
hour after the time when Mlle. Nadiboff had returned.

Jack Benson, however, did not put in an appearance.

The submarine torpedo boat, with its naval party aboard, sailed out of
the harbor, returning just before dark.

Then, as soon as could be, Messrs. Farnum and Pollard and Hal and Eph
came ashore, heading straight for the hotel.

"Your young captain hasn't succeeded in walking the two miles' distance
to this hotel," announced Mr. Hennessy, who was waiting for them.

"Confound it, I don't like the looks of this," muttered Farnum, uneasily.
"It looks as though something had been done to Benson."

"Will you notify the police?" questioned the reporter.

"I don't believe that would be wise. At any rate, not quite yet,"
interposed Hal.

"Then what would you do?" demanded Mr. Farnum, turning upon the young
engineer.

"If Jack has come to any misadventure through that pair of spies,"
uttered Hal, anxiously, "it seems to me it will be a heap more promising
if we keep a sharp, unseen watch over every move made by M. Lemaire
and Mlle. Nadiboff."