“Then you overheard it?” said Hugh.

“Yes, I listened.  Was I not Mademoiselle’s servant?  On that night she had won quite a large sum at the Rooms, and she had given me—­ah! she was always most generous—­five hundred francs—­twenty pounds in your English money.  And they were acceptable in these days of high prices.  I heard much.  I was interested.  Mademoiselle was my mistress whom I had served faithfully.”

“You wondered why this young Englishman should call upon her at that hour?” said The Sparrow.

“I did.  She never received visitors after her five o’clock tea.  It was the habit at the Villa Amette to lunch at one o’clock, English tea at five o’clock, and dinner at eight—­when the Rooms were slack save for the tourists from seven till ten.  Strange!  The tourists always think they can win while the gambling world has gone to its meals!  They get seats, it is true, but they always lose.”

“Yes,” replied The Sparrow.  “It is a strange fact that the greatest losses are sustained by the players when the Rooms are most empty.  Nobody has yet ever been able to account for it.”

“And yet it is so,” declared old Cataldi.  “I have watched it day by day.  But poor Mademoiselle!  What can we do to solve the mystery?”

“Were you not with Mademoiselle and Mr. Benton when you both brought off that great coup in the Avenue Louise, in Brussels?” asked The Sparrow.

“Yes, signore,” said the old man.  “But I do not wish to speak of it now.”

“Quite naturally.  I quite appreciate it.  Since Mademoiselle’s—­er—­accident you have, I suppose, been leading an honest life?”

“Yes.  I have tried to do so.  At present I am a cafe waiter.”

“And you can tell me nothing further regarding the affair at the Villa Amette?” asked The Sparrow, eyeing him narrowly.

“I regret, signore, I can tell you nothing further,” replied the staid, rather sad-looking old man; “nothing.”  And he sighed.

“Why?” asked the man whose tentacles were, like an octopus, upon a hundred schemes, and as many criminal coups in Europe.  He sought a solution of the problem, but nothing appeared forthcoming.

He had strained every effort, but he could ascertain nothing.

That Cataldi knew the key to the whole problem The Sparrow felt assured.  Yet why did not the old fellow tell the truth?

At last The Sparrow rose and left, and Hugh followed him.  Both were bitterly disappointed.  The old man refused to say more than that he was ignorant of the whole affair.

Cataldi’s attitude annoyed the master criminal.

For three days he remained in Nice with Hugh, at great risk of recognition and arrest.

On the fourth day they went together in a hired car along the winding road across the Var to Cannes.

At a big white villa a little distance outside the pretty winter town of flowers and palms, they halted.  The house, which was on the Frejus road, was once the residence of a Russian prince.