-lighted street, suddenly appeared a patrol detachment of the
British provost guard.

"Did you stop the fellow who ran this way, sir?" hailed Ensign Darrin,
as he recognized the uniform of the British infantry officer in
command of the detachment.

"We didn't see any man running this way," replied the British
lieutenant, smartly returning the salute that Ensign Darrin had given
him.

"Didn't _see_ any fellow running?" repeated three Americans, in tones
of bewilderment.

"We were chasing a thief, sir," Darrin continued, "and this waiter
told us that the fugitive ran this way."

"I--I thought he did," stammered the waiter in Spanish, though it was
now plain that he understood English.

In deep disgust and with dawning suspicion, Dave Darrin glared at the
waiter until that fellow changed color and trembled slightly. Dave
was now certain that the waiter, probably by previous arrangement, had
shielded the escape of Mr. Green Hat.

Turning to the English officer, Dave quickly recounted what had
happened. At the same time he introduced himself and Dan as American
naval officers, and both tendered their cards.

"And you, sir? Who are you, and what did you lose?" inquired the
British officer, turning to the young man in the gray suit.

"May I answer that question to an officer of my own country?" appealed
the young man in the gray suit.

"Yes," assented the British officer, after keenly regarding the
stranger who claimed to have been robbed.

"Will you step a few yards down the street with me?" urged the unknown
American, addressing Dave.

"Certainly," Darrin nodded, for he saw insistent appeal in the
stranger's gaze.

"Mr. Darrin," began the stranger, using the name he had heard Dave
announce in the introductions to the Britisher, "do you really belong
to the American Navy?"

"I do, indeed," Darrin answered. "I am attached to the battleship
'Hudson,' now lying in this harbor."

"Then I will introduce myself," continued the young man in the gray
suit. "My name is George Cushing. Do you recognize the meaning of
this?"

"This" proved to be a small gold badge, revealed by Cushing as he
turned back the lapel of his coat. It was a badge worn by men
belonging to a special branch of the secret service of the American
Department of State. The members of this special service are usually
found, if found at all, on duty in foreign countries.

"I know the badge, Mr. Cushing," nodded Dave Darrin. "Now, what have
you