Westerham made his way back to Walter's in a slightly happier frame of mind. He liked to see his difficulties plain before him rather than to be hemmed about with mysteries that he could not understand. And difficulty seemed to be piling itself upon difficulty.

Much, of course, remained to be explained. He was not sure of the different parts which the weirdly associated people whom he had met that afternoon played in Melun's game. He could, however, make a guess, and his shrewd guess was not so wide of the mark.

Bagley, as he had learned from Melun, was the smug manager of a branch of a considerable banking firm. His wife, of course, explained herself. The young man Crow, with the large, cruel, red hands, was probably Melun's principal striking force in times of trouble. The captain himself, he imagined, furnished the brains, while Bagley supplied the finance.

But what of Mme. Estelle? That she had her part allotted to her in the strange drama unfolding itself Westerham could not doubt. But what part?

Some parts that he could conceive were almost too unpleasant to think of. Putting the thing at its best, he could not imagine that Mme. Estelle acted as less than a lure.

But what tie bound her to Melun? What tie kept her within the confines of this strange collection of human beings?

For a moment Westerham's heart grew light within him. It was possible that the tie was connected with Captain Melun. Was she his wife? If he could but establish that, then the captain's boast that he would marry Lady Kathleen was vain indeed.

Westerham decided to inquire.

He was most eager to discover the ways in which Melun and his confederates worked. If he had, indeed, been free to follow his course of curiosity unfettered he would have gone steadily forward until he had discovered the uttermost of their wrong-doing. He was, however, from the outset balked by the problem presented by Lady Kathleen, and he realised at once that it was upon the solution of this that he must set his whole mind.

Sir Paul was, indeed, confronted by a very Gordian knot of problems. He laughed a little as he made the simile to himself, until he reflected that he was not an Alexander armed with a sword who could disperse the problems at one blow. His, indeed, would be the laborious task of unravelling them one by one; nor could he see any better way than by beginning at the very beginning, which, so far as he was concerned, meant a full knowledge of Melun's intimates and surroundings.

He was quick to see that, with all the possibilities offered by a great organisation of crime, Melun must of necessity have a certain number of hardier spirits than those represented by Bagley, Mme. Estelle, or even Crow to do his rough-and-ready work. Westerham resolved to know these rough-and-readier spirits at once.

That night he did nothing except to wander down to Downing Street and stand for a little while thinking over matters at the corner of Whitehall. He stood there, indeed, for an unwise length of time, so that at last he drew upon himself the attention of the constable stationed on point duty. Perceiving this Westerham turned and walked back to his hotel, where he did his best to amuse himself by aimlessly meandering through the pages of various newspapers.

Knowing, too, that Lady Kathleen stood sufficiently in the world's eye to merit the attention of the Press, Westerham instinctively turned towards those columns which deal with the doings of Society. Nor was his search unrewarded, for before long he came across a paragraph which set forth that the Prime Minister and his daughter, the Lady Kathleen Carfax, would in two days' time give a great reception at Lord Penshurst's official residence in Downing Street.

“Now,” said Westerham to himself, “I shall see to what extent Melun speaks the truth. For, unless he is a liar, I will go to that reception myself.”

Therefore he sat down and wrote a note to Melun requesting him to call after lunch the next day.

In due course Melun came, and Westerham proceeded to speak to him on the lines he had mapped out for himself the day before. Much, indeed, to the captain's discomfort, he advanced his theory that Melun had confederates of an entirely different type from the Bagleys and Mme. Estelle.

“In fact,” said the baronet, fixing his unpleasantly cold sea-green gaze on Melun's shifting eyes, “it is practically useless for you to dispute my arguments, and if you have any hope of my fulfilling my part of the bargain you had better introduce me to them without delay.”

Melun laughed. It was a habit of his to laugh when embarrassed.

“Really,” he said with a slightly bantering air, “you are almost too swift for me. Believe me, you are dangerously quick. It is most unwise for a man to plunge suddenly into an acquaintance with the various kinds of undesirable people which it is my misfortune to know.

“They are rather touchy about their privacy, and they are apt actively to resent intrusion. I should leave them alone. Personally, I dislike fuss of every description, but especially the kind of fuss which hurts physically.”

Then he caught a slight sneer on Westerham's mouth and reddened a little. He reddened still more when the baronet said shortly, “I thought so.”

Melun's composure, however, returned to him almost instantly. “Come, come,” he said, “it is foolish to be nasty to your friends. We all have our little failings. I have mine. Yours, it seems, is rashness; mine may be timidity. It is purely a question of constitution.”

“Constitution,” said Westerham, grimly, “is largely a question of degrees of force. On this occasion I think that force will win. Please understand me distinctly that, however rash you may think me, however foolish my haste may appear, I am determined to see the rest of your organisation without further delay.”

Melun shrugged his shoulders.

“So be it,” he said; “we shall want a couple of caps, and you will have to turn your collar up. Not even the comparatively humble bowler is particularly acceptable in Limehouse.”

“Limehouse!” exclaimed Westerham. And he smiled a pleased little smile to himself. Events were developing themselves in a sufficiently melodramatic way to be entertaining. “Limehouse,” he said again. “I was there yesterday.”

Melun drew in his breath sharply and bared his teeth in an unpleasant snarl.

“Have you been spying?” he asked coarsely.

“I don't spy,” said Westerham, coldly.

And that was sufficient.

The two men ate a rather gloomy dinner in the small hotel. Conversation lagged, for as yet they had not much in common. Each of them, however, from a different point of view, was soon to have far too much in common with the other.

Towards eight o'clock Melun rose and suggested that they should be going. Westerham provided him with a cap, and having pulled their coat collars about their ears, they climbed on board one of the Blackwall motor omnibuses.

On this they travelled as far as Leman Street, where Melun descended from the omnibus roof. Westerham followed at his heels.

They then took a tram, and for what seemed to Westerham an interminable time they travelled slowly eastward along the Commercial Road. Presently a great white tower threw into greater blackness the surrounding black of the murky sky. Westerham, as the result of his recent experiences in the East End, knew the tower to be that of Limehouse church.

Here they again alighted, and Melun walked quickly down that curious street which is known as Limehouse Cut.

Gas lamps standing at long intervals threw a very feeble and flickering light upon the small, low-built shops which traverse its western side. The light, however, was sufficient to show the curious hieroglyphics which proclaimed the tenants of those shops to be Chinese.

At the bottom of Limehouse Cut Melun turned sharp to the right, and in a little space set back from the road Westerham found himself surveying yet another of the queer little hieroglyphic-ridden shops. But there was a difference, for whereas the others were low built, this was some four storeys high. The door, too, instead of being glass-panelled, was of solid wood, and apparently of great strength.

On this Melun knocked sharply with his knuckles nine times, the first three raps being slow, the second three raps being slow, and the last three raps being quick and decisive.

Almost immediately the door swung noiselessly inwards, while from behind its corner appeared the searching, slumberous eyes of a great nigger.

The nigger was about to let Melun pass when he saw Westerham, and with a mighty arm barred the way.

“All right, all right,” said Melun, quickly. “You don't suppose that I am fool enough to bring a man here whom I cannot trust. Let him in at once.”

The negro shuffled back and allowed Westerham to squeeze himself into the narrow passage.

It was intensely dark, so the negro lifted the lantern, the slide of which had been placed hard against the wall, and held it on a level with Sir Paul's head, looking at him long and narrowly.

Then he gave a little coughing groan and shambled down the passage.

At the end of the passage the huge negro opened a second door, which swung back upon its hinges as easily and as swiftly as the first. Westerham passed into the room, and with a little thump of his heart realised, with a knowledge born of long experience of the Pacific coast, that he was in an opium den of quite unusual dimensions.

The long room ran parallel with the front of the house, but must have been some thirty feet longer than the front of the house itself. On either side and at both ends there were tiers of bunks. From three or four of them came a little red glow where some besotted fool still sucked at his pipe.

No pause, however, was made here. The negro crossed the room and opened a third door, which admitted them into a small passage. At the end of this a fourth door was opened, and Melun and Westerham stepped suddenly into a blaze of light.

Looking quickly about him, Westerham judged himself to be in a working-man's club. Half a dozen men were playing pool at a dilapidated table, while round about were little groups of men playing dominoes or cards. Framed notices set forth various rules, while at one end of the room stretched a bar.

The negro, still with the light in his hand, stood aside watching Melun uneasily. Westerham was quick to observe that he had his hand on his hip-pocket. And his smile was slightly amused and slightly anxious as one of the players looked up and gave a little cry, his cue falling from his hand and his hand going quickly to his hip also.

But Melun was first, and the revolver which he had whipped out covered the man's breast.

The man's cry aroused the instant attention of the others, and for a few moments there was what can only be described as a sort of hushed hubbub.

“All right,” said Melun in a rougher voice than Westerham had yet heard him use. “All right. Don't get scared. Don't worry. It is a new chum!”

Westerham, standing very straight, stood smiling at the astonished men before him.

The negro had set his lantern down, and was passively leaning with his back against the door.

A little man with a bullet-head and a red face got up from his seat at the end of the room and came forward with short, quick, jerky steps.

“Is this going to be a meeting?” he asked.

Melun nodded. “A meeting,” he said, “but not an oath. That I already have administered in part. The new chum is silent.”

“It is most irregular,” grumbled the man with the bullet-head.

“Never you mind,” said Melun in a hectoring voice, “it is my affair, and not yours.”

“It is our business that you bring him here,” mumbled several of the men.

“Don't you bother about things which do not concern you,” rapped out Melun, “until I have had my say. I have said this is to be a meeting, and I am waiting to give my explanation.”

At this several men turned and dragged forward a long trestle table, while others quickly set chairs about it; Melun seated himself at its head, beckoning to Westerham to seat himself at his right hand.

Still smiling, Westerham looked with his oddly disconcerting gaze along the row of faces before him. Melun, he reflected, must have searched London to have found such an exhibition of evil passions.

The men did not look at him; they looked at Melun, warily and anxiously.

“In times past,” said Melun, shortly, “you have found it just as well to trust to me. The shares of any spoils we have won have always been fairly adjusted.”

For the most part the men nodded assent.

“I have told you,” Melun continued, “that at the present time I have on hand a bigger deal than any I have yet attempted. If it comes off it will mean a cool quarter of a million.”

Westerham drew in his breath quietly; he was learning the facts indeed. The magnitude of what Melun must have at stake almost staggered him. He knew well enough that if Melun spoke to these men of a quarter of a million, the sum at which he was really aiming must be far greater.

“Now, most of you,” Melun went on, “know that to pull off a thing of this sort capital is required. Our capital has run low. I have, however, been fortunate in securing the interest of this gentleman, who is more than able to furnish us with all the money I need to settle the deal.

“I may tell you that he is not new to our kind of work, only hitherto he has gone on his own.”

The men round the table nodded approval, and Westerham, while he marvelled at Melun's audacity, flushed a trifle angrily. It was unpleasant to be tarred with the same brush as these fellows. But he saw that he must sit it through.

“Now, the very fact that this gentleman has taken part in this sort of business before,” Melun went on boldly, “made him suspicious of our good faith, and he asked for an actual demonstration that we were a working concern, and he would not be satisfied until I had proved it to him. I should, of course, have asked your permission to bring him here first, but the matter is most urgent. The fate of the whole thing may have to be settled to-morrow night.”

He paused, and Westerham's blood began to run quickly through his veins.

To-morrow night! To-morrow night the Prime Minister and Lady Kathleen gave their great reception.

To-morrow night! Sir Paul wondered what connection there might be between Downing Street and Limehouse. Melun, however, continued to speak in the same suave tones.

“To-morrow, as I say,” he declared, “may settle the whole affair. Before to-morrow night I have to show this gentleman—whose name, I may inform you, is James Robinson—that we are really in earnest.

“Mr. Robinson,” he cried, turning towards Westerham, “are you satisfied?”

“I am,” said Westerham, in a very quiet voice, allowing himself just enough of American drawl to catch some of the quick ears of his listeners.

“From the States?” asked the man who sat next to him.

Westerham nodded.

Melun gave Westerham's interrogator a look as though he resented any attempt at conversation; and to prevent any further questioning he rose abruptly from the table.

The rest of the men remained seated except the bullet-headed man, who, as Melun vacated his chair, slipped into his place. They were apparently about to discuss other matters, and were following the ordinary course of procedure.

Seeing Melun rise, the negro, who all this time had been leaning against the door, lifted up his lantern again and showed them out.

They passed through the opium den, and so into the little passage, when, as the negro was fumbling at the door, Westerham heard a long, piercing scream.

It came again louder and shriller than before. There was a dreadful note of fear in it. It was the scream of a terrified girl.