“No, though I thank you, Mademoiselle,” he replied.  “Captain Benson will doubtless be here before we could make a fair start.”

Nodding pleasantly, the Russian vanished through the ladies’ entrance.  Hal went back to his companions.

“Say,” broke in Eph, presently, “if she left Jack to go several miles for her luncheon, she got it and returned mighty quick.”

“Probably used a woman’s privilege, and changed her mind about driving to that other hotel,” suggested Mr. Farnum.

For some minutes more the party waited, then went down into the road, but there was no sign of Jack coming along.

“Mighty strange!” muttered Hal, uneasily.  “Well, we’ve got to aboard, now,” announced Jacob Farnum, after glancing at his watch.  “Sorry we can’t very well invite you to go with us, Mr. Hennessy.”

“I shall see you, if you come ashore in the evening,” replied the reporter.  “In the meantime I shall be about the hotel.  If I see Benson, I’ll tell him where you all are.”

Being well provided with cigars, Reporter Hennessy did not quit the veranda after he had once taken his seat there.  So it happened that 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.”

“Right-o, every time!” clicked Eph.  “If anything has happened to good old Jack through that pair, then they’re the only ones to be watched!”

Dinner, that evening, wasn’t as confident a meal for the submarine party as luncheon had been.  Both Mlle. Nadiboff and the Frenchman were in the dining room, though they did not sit together.

Later, the young Russian woman appeared in the ballroom.  She was as eagerly sought as a partner as she had been the night before.

Farnum and his friends did not enter the ballroom, not having brought evening dress ashore with them.