"It was all right," he said. "The police were very kind. Miss Joan Carew told her story to them as she had told it to us. Fortunately, the envelope with the aluminium chain had already been delivered, and was in their hands. They were much mystified about it, but Miss Joan's story gave them a reasonable explanation. I think they are inclined to believe her; and, if she is speaking the truth, they will keep her out of the witness-box if they can."

"She is to stay here in London, then?" asked Ricardo.

"Oh, yes; she is not to go. She will present her letters at the Opera House and secure an engagement, if she can. The criminals might be lulled thereby into a belief that the girl had kept the whole strange incident to herself, and that there was nowhere even a knowledge of the disguise which they had used." Hanaud spoke as carelessly as if the matter was not very important; and Ricardo, with an unusual flash of shrewdness, said:

"It is clear, my friend, that you do not think those two men will ever be caught at all."

Hanaud shrugged his shoulders.

"There is always a chance. But listen. There is a room with a hundred guns, one of which is loaded. Outside the room there are a hundred pigeons, one of which is white. You are taken into the room blind-fold. You choose the loaded gun and you shoot the one white pigeon. That is the value of the chance."

"But," exclaimed Ricardo, "those pearls were of great value, and I have heard at a trial expert evidence given by pearl merchants. All agree that the pearls of great value are known; so, when they come upon the market----"

"That is true," Hanaud interrupted imperturbably. "But how are they known?"

"By their weight," said Mr. Ricardo.

"Exactly," replied Hanaud. "But did you not also hear at this trial of yours that pearls can be peeled like an onion? No? It is true. Remove a skin, two skins, the weight is altered, the pearl is a trifle smaller. It has lost a little of its value, yes--but you can no longer identify it as the so-and-so pearl which belonged to this or that sultan, was stolen by the vizier, bought by Messrs. l.u.s.tre and Steinopolis, of Hatton Garden, and subsequently sold to the wealthy Mrs. Blumenstein. No, your pearl has vanished altogether. There is a new pearl which can be traded." He looked at Ricardo. "Who shall say that those pearls are not already in one of the queer little back streets of Amsterdam, undergoing their transformation?"

Mr. Ricardo was not persuaded because he would not be. "I have some experience in these matters," he said loftily to Hanaud. "I am sure that we shall lay our hands upon the criminals. We have never failed."

Hanaud grinned from ear to ear. The only experience which Mr. Ricardo had ever had was gained on the sh.o.r.es of Geneva and at Aix under Hanaud's tuition. But Hanaud did not argue, and there the matter rested.

The days flew by. It was London's play-time. The green and gold of early summer deepened and darkened; wondrous warm nights under England's pale blue sky, when the streets rang with the joyous feet of youth, led in clear dawns and lovely glowing days. Hanaud made acquaintance with the wooded reaches of the Thames; Joan Carew sang "Louise" at Covent Garden with notable success; and the affair of the Semiramis Hotel, in the minds of the few who remembered it, was already added to the long list of unfathomed mysteries.

But towards the end of May there occurred a startling development.

Joan Carew wrote to Mr. Ricardo that she would call upon him in the afternoon, and she begged him to secure the presence of Hanaud.

She came as the clock struck; she was pale and agitated; and in the room where Calladine had first told the story of her visit she told another story which, to Mr. Ricardo's thinking, was yet more strange and--yes--yet more suspicious.

"It has been going on for some time," she began. "I thought of coming to you at once. Then I wondered whether, if I waited--oh, you'll never believe me!"

"Let us hear!" said Hanaud patiently.

"I began to dream of that room, the two men disguised and masked, the still figure in the bed. Night after night! I was terrified to go to sleep. I felt the hand upon my mouth. I used to catch myself falling asleep, and walk about the room with all the lights up to keep myself awake."

"But you couldn't," said Hanaud with a smile. "Only the old can do that."

"No, I couldn't," she admitted; "and--oh, my nights were horrible until"--she paused and looked at her companions doubtfully--"until one night the mask slipped."

"What--?" cried Hanaud, and a note of sternness rang suddenly in his voice. "What are you saying?"

With a desperate rush of words, and the colour staining her forehead and cheeks, Joan Carew continued:

"It is true. The mask slipped on the face of one of the men--of the man who held me. Only a little way; it just left his forehead visible--no more."

"Well?" asked Hanaud, and Mr. Ricardo leaned forward, swaying between the austerity of criticism and the desire to believe so thrilling a revelation.

"I waked up," the girl continued, "in the darkness, and for a moment the whole scene remained vividly with me--for just long enough for me to fix clearly in my mind the figure of the apache with the white forehead showing above the mask."

"When was that?" asked Ricardo.

"A fortnight ago."

"Why didn't you come with your story then?"

"I waited," said Joan. "What I had to tell wasn't yet helpful. I thought that another night the mask might slip lower still. Besides, I--it is difficult to describe just what I felt. I felt it important just to keep that photograph in my mind, not to think about it, not to talk about it, not even to look at it too often lest I should begin to imagine the rest of the face and find something familiar in the man's carriage and shape when there was nothing really familiar to me at all. Do you understand that?" she asked, with her eyes fixed in appeal on Hanaud's face.

"Yes," replied Hanaud. "I follow your thought."

"I thought there was a chance now--the strangest chance--that the truth might be reached. I did not wish to spoil it," and she turned eagerly to Ricardo, as if, having persuaded Hanaud, she would now turn her batteries on his companion. "My whole point of view was changed. I was no longer afraid of falling asleep lest I should dream. I wished to dream, but----"

"But you could not," suggested Hanaud.

"No, that is the truth," replied Joan Carew. "Whereas before I was anxious to keep awake and yet must sleep from sheer fatigue, now that I tried consciously to put myself to sleep I remained awake all through the night, and only towards morning, when the light was coming through the blinds, dropped off into a heavy, dreamless slumber."

Hanaud nodded.

"It is a very perverse world, Miss Carew, and things go by contraries."

Ricardo listened for some note of irony in Hanaud's voice, some look of disbelief in his face. But there was neither the one nor the other.

Hanaud was listening patiently.

"Then came my rehearsals," Joan Carew continued, "and that wonderful opera drove everything else out of my head. I had such a chance, if only I could make use of it! When I went to bed now, I went with that haunting music in my ears--the call of Paris--oh, you must remember it. But can you realise what it must mean to a girl who is going to sing it for the first time in Covent Garden?"

Mr. Ricardo saw his opportunity. He, the connoisseur, to whom the psychology of the green room was as an open book, could answer that question.

"It is true, my friend," he informed Hanaud with quiet authority. "The great march of events leaves the artist cold. He lives aloof. While the tumbrils thunder in the streets he adds a delicate tint to the picture he is engaged upon or recalls his triumph in his last great part."

"Thank you," said Hanaud gravely. "And now Miss Carew may perhaps resume her story."

"It was the very night of my debut," she continued. "I had supper with some friends. A great artist. Carmen Valeri, honoured me with her presence. I went home excited, and that night I dreamed again."

"Yes?"

"This time the chin, the lips, the eyes were visible. There was only a black strip across the middle of the face. And I thought--nay, I was sure--that if that strip vanished I should know the man."

"And it did vanish?"

"Three nights afterwards."

"And you did know the man?"

The girl's face became troubled. She frowned.

"I knew the face, that was all," she answered. "I was disappointed. I had never spoken to the man. I am sure of that still. But somewhere I have seen him."

"You don't even remember when?" asked Hanaud.