Ayscough had only time to give a warning look and a word to the others before Mr. Mori Yada was ushered in. Every eye was turned on him as he entered--some of the men present looking at him with wonder, some with curiosity, two, at any rate--Levendale and Stephen Purvis--with doubt. But Yada himself was to all outward appearance utterly indifferent to the glances thrown in his direction: it seemed to John Purdie, who was remembering all he had heard the night before, that the young Japanese medical student was a singularly cool and self-possessed hand. Yada, indeed, might have been walking in on an assemblage of personal friends, specially gathered together in his honour. Melky Rubinstein, who was also watching him closely, noticed at once that he had evidently made a very careful toilet that morning. Yada's dark overcoat, thrown negligently open, revealed a smart grey lounge suit; in one gloved hand he carried a new bowler hat, in the other a carefully rolled umbrella. He looked as prosperous and as severely in mode as if no mysteries and underground affairs had power to touch him, and the ready smile with which he greeted Ayscough was ingenuous and candid enough to disarm the most suspicious.

"Good morning, Mr. Detective," he began, as he crossed the threshold and looked first at Ayscough and then at the ring of attentive faces. "I want to speak to you on that little affair of last night, you know. I suppose you are discussing it with these gentlemen? Well, perhaps I can now give you some information that will be useful."

"Glad to hear anything, Mr. Yada," said Ayscough, who was striving hard to conceal his surprise. "Anything that you can tell us. You've heard something during the night, then?"

Yada laughed pleasantly, showing his white teeth. He dropped into the chair which Ayscough pushed forward, and slowly drew off his gloves.

"I assured myself of something last night--after you left me," he said, with a knowing look. "I used your card to advantage, Mr. Detective. I went to the mortuary."

Ayscough contrived to signal to the Inspector to leave the talking to him. He put his thumbs in the armholes of his waistcoat, assumed an easy attitude as he leaned against the door, and looked speculatively at the new comer.

"Aye?--and what made you do that now, Mr. Yada?" he asked, half- carelessly. "A bit of curiosity, eh?"

"Not idle curiosity, Mr. Detective," replied Yada. "I wanted to know, to make certain, which of the two Chinamen it really was who was there--dead. I saw him. Now I know. Chen Li!"

"Well?" said Ayscough.

Yada suddenly twisted round in his chair, and slowly glanced at the listening men on either side of the desk. They were cool, bold, half- insolent eyes which received face after face, showing no recognition of any until they encountered Melky Rubinstein's watchful countenance. And to Melky, Yada accorded a slight nod--and turned to Ayscough again.

"Which," he asked calmly, "which of these gentlemen is the owner of the diamond? Which is the one who has lost eighty thousand pounds in bank- notes? That is what I want to know before I say more."

In the silence which followed upon Ayscough's obvious doubt about answering this direct question, Levendale let out a sharp, half-irritable exclamation:

"In God's name!" he said, "who is this young man? What does he know about the diamond and the money?"

Yada turned and faced his questioner--and suddenly smiling, thrust his hand in his breast pocket and drew out a card-case. With a polite bow he handed a card in Levendale's direction.

"Permit me, sir," he said suavely. "My card. As for the rest, perhaps Mr. Detective here will tell you."

"It's this way, you see, Mr. Levendale," remarked Ayscough. "Acting on information received from Dr. Pittery, one of the junior house-surgeons at University College Hospital, who told me that Mr. Yada was a fellow- student of those two Chinese, and a bit of a friend of theirs, I called on Mr. Yada last night to make enquiries. And of course I had to tell him about the missing property--though to be sure, that's news that's common to everybody now--through the papers. And--what else have you to tell, Mr. Yada?"

But Yada was watching Levendale--who, on his part, was just as narrowly watching Yada. The other men in the room watched these two--recognizing, as if by instinct, that from that moment matters lay between Levendale and Yada, and not between Yada and Ayscough. They were mutually inspecting and appraising each other, and in spite of their impassive faces, it was plain that each was wondering about his next move.

It was Levendale who spoke first--spoke as if he and the young Japanese were the only people in the room, as if nothing else mattered. He bent forward to Yada.

"How much do you know?" he demanded.

Yada showed his white teeth again.

"A plain--and a wide question, Mr. Levendale!" he answered, with a laugh. "I see that you are anxious to enlist my services. Evidently, you believe that I do know something. But--you are not the owner of the diamond! Which of these gentlemen is?"

Levendale made a half impatient gesture towards Stephen Purvis, who nodded at Yada but remained silent.

"He is!" said Levendale, testily. "But you--can do your talking to me. Again--how much do you know in this matter?"

"Enough to make it worth your while to negotiate with me," answered Yada. "Is that as plain as your question?"

"It's what I expected," said Levendale. "You want to sell your knowledge."

"Well?" assented Yada, "I am very sure you are willing to purchase."

Once more that duel of the eyes--and to John Purdie, who prided himself on being a judge of expressions, it was evident that the younger man was more than the equal of the older. It was Levendale who gave way--and when he took his eyes off Yada, it was to turn to Stephen Purvis.

Stephen Purvis nodded his head once more--and growled a little.

"Make terms with him!" he muttered. "Case of have to, I reckon!"

Levendale turned once more to the Japanese, who smiled on him.

"Look you here, Mr. Yada," said Levendale, "I don't know who you are beyond what I'm told--your card tells me nothing except that you live-- lodge, I suppose--in Gower Street. You've got mixed up in this, somehow, and you've got knowledge to dispose of. Now, I don't buy unless I know first what it is I'm buying. So--let's know what you've got to sell?"

Yada swept the room with a glance.

"Before these gentlemen?" he asked. "In open market, eh?"

"They're all either police, or detectives, or concerned," retorted Levendale. "There's no secret. I repeat--what have you got to sell? Specify it!"

Yada lifted his hands and began to check off points on the tips of his fingers.

"Three items, then, Mr. Levendale," he replied cheerfully. "First--the knowledge of who has got the diamond and the money. Second--the knowledge of where he is at this moment, and will be for some hours. Third--the knowledge of how you can successfully take him and recover your property. Three good, saleable items, I think--yes?"

Purdie watched carefully for some sign of greed or avarice in the informer's wily countenance. To his surprise, he saw none. Instead, Yada assumed an almost sanctimonious air. He seemed to consider matters--though his answer was speedy.

"I don't want to profit--unduly--by this affair," he said. "At the same time, from all I've heard, I'm rendering you and your friend a very important service, and I think it only fair that I should be remunerated. Give me something towards the expenses of my medical education, Mr. Levendale: give me five hundred pounds."

With the briefest exchange of glances with Stephen Purvis, Levendale pulled out a cheque-book, dashed off a cash cheque, and handed it over to the Japanese, who slipped it into his waistcoat pocket.

"Now--your information!" said Levendale.

"To be sure," replied Yada. "Very well. Chang Li has the diamond and the money. And he is at this moment where he has been for some days, in hiding. He is in a secret room at a place called Pilmansey's Tea Rooms, in Tottenham Court Road--a place much frequented by medical students from our college. The fact of the case is, Mr. Policeman, and the rest of you generally, there is a secret opium den at Pilmansey's, though nobody knows of it but a few frequenters. And there!--there you will find Chang Li."

"You've seen him there?" demanded Levendale.

"I saw him there during last night--I know him to be there--he will be there, either until you take him, or until his arrangements are made for getting out of this country," answered Yada.

Levendale jumped up, as if for instant action. But the Inspector quietly tapped him on the elbow.

"He promised to tell you how to take him, Mr. Levendale," he said. "Let's know all we can--we shall have to be in with you on this, you know."

"Mr. Police-Inspector is right," said Yada. "You will have to conduct what you call a raid. Now, do precisely what I tell you to do. Pilmansey's is an old-fashioned place, a very old house as regards its architecture, on the right-hand side of Tottenham Court Road. Go there today--this mid-day --a little before one--when there are always plenty of customers. Go with plenty of your plain-clothes men, like Mr. Ayscough there. Drop in, don't you see, as if you were customers--let there be plenty of you, I repeat. There are two Pilmanseys--men--middle-aged, sly, smooth, crafty men. When you are all there, take your own lines--close the place, the doors, if you like--but get hold of the Pilmansey men, tell them you are police, insist on being taken to the top floor and shown their opium den. They will object, they will lie, they will resist--you will use your own methods. But--in that opium den you will find Chang Li--and your property!"

He had been drawing on his gloves as he spoke, and now, picking up his hat and umbrella, Yada bowed politely to the circle and moved to the door.

"You will excuse me, now?" he said. "I have an important lecture at the medical school which I must not miss. I shall be at Pilmansey's, myself, a little before one--please oblige me by not taking any notice of me. I do not want to figure--actively--in your business."

Then he was gone--and the rest of them were so deeply taken with the news which he had communicated that no one noticed that just before Yada fastened his last glove-button, Melky Rubinstein slipped from his corner and glided quietly out of the room.