On their way to the hotel, Brett, yielding apparently to a momentary impulse, stopped the cab at a house in the Rue du ChaussÉe d'Antin. Without any explanation to Lord Fairholme he disappeared into the interior, and did not rejoin his companion for nearly ten minutes.

"It is perhaps not of much use," he explained on his return, "but I do not like to leave any stone unturned. The man I have just called on is a well-known private detective, and I can trust him to look after my business without taking the police into his confidence. Two of his smartest agents will maintain a close watch on both the Cabaret Noir and No. 11, Rue Barbette, during the afternoon."

"You do not seem to expect much result?"

"No; we are tracking some of the most expert and daring criminals in France. It is hopeless to expect them to provide us with clues; they simply won't do it. No one but a genius in criminality would have risked such a dramatic move as the personation of Jack Talbot, or dared to put in an open appearance at the Grand Hotel. So my agents here can only hope, at the best, to get sight of any messenger or assistant scoundrel who may turn up at either of the places indicated."

"May we expect to be busy to-night?"

Brett did not answer at once. It was evident that whilst he rattled on in a careless strain his active brain was busily employed in discounting the future.

"I hope so," he said at last. "Of course I cannot tell. Our only chance is that we may be able to guess the course of the hidden trail. If to-night does not yield us some information, our chances of solving the mystery will be remote, in which case we may as well abandon the quest."

This faint-hearted reply naturally surprised Lord Fairholme considerably. To his mind, a considerable measure of success had already been achieved, and he utterly failed to understand why his friend should take such a pessimistic view of affairs at the very moment when they appeared to be opening up somewhat. Brett noted the Earl's perplexity, and smiled with genial deprecation.

"Do not be afraid, Fairholme; I will liberate Mr. Talbot and clear his name so effectually that all difficulties will disappear from the path of your marriage."

"Then what is it that makes you so downcast?" cried Fairholme.

"I hate to be beaten at the final stage, and I have a premonition that were I in England—had I but the power to proceed unchecked and unhindered by officialdom—I would soon lay my hands on the man who originated the Albert Gate mystery. But we are in France—in a country of queer legal forms and unusual methods. At home I can always circumvent Scotland Yard; here I am in the midst of strange surroundings, and know not what may happen. Therefore, we must possess our souls in patience and wait developments. The agent I have just employed has promised me to report every two hours at the hotel until eight o'clock. Then I will take personal charge of the Cabaret Noir, and——"

"What about me?" cried Fairholme.

"You, my dear fellow, will remain at the hotel and await orders."

This arrangement did not seem to suit the active young Englishman who had been so suddenly plunged into the excitement of a criminal chase in Paris.

"Really, Brett," he said, "I hate to grumble at anything you propose, because you are always right; but you must pardon me for saying that I do not see what particular value my presence here has been to you."

"What!" laughed Brett; "not after your dramatic appearance in the Rue Barbette this morning?"

"Oh, any one could have done that. All I had to do was to break in a door at a given hour."

"Exactly," said Brett gravely. "I wanted a friend whom I could trust to implicitly obey my orders, and you did it. I am sure you will fall in with my wishes now."

So Fairholme was silenced on this point, but he ventured to put another question.

"How long am I to sit chewing cigars in our rooms, then?"

"All night, if necessary. If I do not appear by seven o'clock to-morrow morning you had better go to the Embassy and tell one of the secretaries everything connected with our visit to Paris. He will then take action through the police in proper form, and after that you must simply await developments."

"Do you mean to say," said Fairholme, anxiously, "that you are contemplating another risky bit of business to-night?"

"Once I take my stand outside the Cabaret Noir about 8.30 I cannot tell where Fate may lead me. If I am lucky I will certainly return, whatever be the personal outcome. If, on the other hand, I learn nothing, you may certainly expect to see me about two in the morning."

At the hotel Brett found awaiting him a letter delivered by the midday post. It was from his elderly assistant in London, whom he had told to make a close scrutiny of all inhabited houses within a certain radius of the Carlton Hotel. The man had done his work systematically, and in only three instances was he called on to report doubtful cases.

Two foreign restaurants in side streets contained a number of residents concerning whom it was difficult to obtain specific information.

One of these establishments he believed to be the resort of Continental gamblers driven from Soho by the too marked attentions of the police. The other was a place of even more questionable repute, and in both instances he had utterly failed to obtain the slightest information from the servants, who apparently "stood in" with the management.

The third dwelling which courted observation was a flat situated above some business premises in another quiet street. So far as he could learn, it was tenanted by an elderly lady who was a helpless invalid, waited on by a somewhat curious couple.

"They are Italians, I think," wrote the ex-policeman, "and very uncommunicative people. I have twice called, on one pretext or another, but when the door is opened it is always kept on the chain, and I cannot see more than the face of a man or woman and a few inches of wall beyond. Still, I have no reason to doubt that the view taken by the milkman and baker is correct, namely, that the owner of the flat is confined to her bed and is suffering from a nervous disease, which renders it imperative she should be shut off from all noise. The landlord informs me that these people have occupied the place for nearly two months. Their rent is paid in advance, and they have not given the slightest cause for complaint. There are, of course, in this district a large number of private hotels and lodging-houses, but they seem to be run on regular lines, and, although some of their patrons might well demand closer observation, I have come across nothing suggestive of any suspicious circumstance whatever with reference to them. I have detained my report until I was able to give details concerning the other houses in the district, and I will now fall back on the second part of your instructions, i.e., to maintain a close watch on the three establishments which I have picked out as being more unusual in their habits than the others."

This was all.

Brett read the concluding portion of the report to Fairholme.

"He is a level-headed, shrewd observer," he said—"one of the few men whom I can trust to do exactly what I want, neither more nor less. I think when we return to London we must endeavour to get that chain taken off the invalid lady's door, or, at any rate, obtain some specific facts concerning her disease from her medical adviser."

Fairholme smiled. "I am glad to hear," he cried, "that you do anticipate our return."

"Oh," said Brett airily, "I never count on failure."

Soon after three o'clock a report arrived from the agent in the Rue du ChaussÉe d'Antin. It read—

"What is the meaning of 'Le Ver'?" said Fairholme.

"It means 'The Worm,'" answered Brett.

"I must say these chaps do find suitable nicknames for one another. I wonder if he is the fellow we followed to Montmartre this morning?"

"Possibly, though I am puzzled to understand why he should trust himself in that hornets' nest again. Most certainly the description covers him, but we shall probably hear more details later. I wonder where the Turkish gentleman went whom 'Le Ver' seems to have followed. He could not have gone to the Cabaret Noir in the time?"

Brett's curiosity was answered to some extent by the next report, delivered about five o'clock. It read as follows—

At seven o'clock came developments.

"Now I wonder," said Brett, "why the Turks left the Frenchman alone in No. 11. It is odd, to say the least of it. Since the dramatic discovery of the spurious diamonds this morning they must be even more in the dark than I am. It must be looked into, but I cannot attend to it now. At this moment, if I am not mistaken, the centre of interest is the CafÉ Noir."

The two men occupied a sitting-room on the first floor of the hotel, and their respective bedrooms flanked it on each side. Brett explained that he could not tackle the table d'hote dinner, so he made a hasty meal in their sitting-room and then excused himself whilst he retired to his bedroom to change his clothing.

He was absent some twenty minutes, and Fairholme amused himself by glancing over the copies of the day's London newspapers which had recently arrived. Suddenly the door of Brett's bedroom opened, and a decrepit elderly man appeared, a shabby-genteel individual, disfigured by drink and crumpled up by rheumatism.

"Who the devil——" began Fairholme.

But he was amazed to hear Brett's familiar voice asking—

"Do you think the disguise sufficiently complete?"

"Complete!" shouted Fairholme, "why, your own mother would not know you, and your father would probably punch me for suggesting that it could be you."

"That is all right," said the barrister cheerfully. "I will now proceed to get quietly drunk at the CafÉ Noir. Good-bye until seven o'clock to-morrow morning—perhaps earlier, and perhaps—well, no—until seven o'clock!"

They shook hands and parted, and not even Brett, the cleverest amateur detective of his day, could have remotely guessed where and how they would meet next.

Montmartre by day and Montmartre by night are two very different places. This Parisian playground, perched high on the eminence that overlooks the Ville LumiÈre, does not wake to its real life until its repose is disturbed by the lamplighter. Then the Moulin Rouge, festooned with lamps of gorgeous red, flares forth upon an expectant world. The CafÉ de l'Enfers opens its demoniac mouth to swallow ten minutes' audiences and vomit them forth again, amused or bored, as the case may be, by the delusions provided in the interior, whilst other questionable resorts shout forth their attractions and seek to beguile a certain number of sous from the pockets of sightseers.

The whole district is a place of light and shade. It is artificial in every brick and stone, in the pose of every stall, the lettering of every advertisement. And it flourishes by gaslight; by day it is garish and forlorn.

Prominent among the regular houses of entertainment was the Cabaret Noir, which, between the hours of 9 p.m. and 1 a.m., usually drove a roaring trade. Situated in the heart of a mountebank district, its patrons embraced all classes of society, from the American tourist with his quick eyes noting the vagaries of demi-mondaines, to the sharp-witted Parisian idler, on the alert for any easy and dishonest method of obtaining money which might present itself.

Among such a crowd a wine-sodden and decrepit old man was not likely to attract particular attention.

He sprawled over the table close to one of the windows which commanded a view of the side passage leading to the rear of the building. Although none of the noisy crowd in the cafÉ could suspect the fact, the half-closed eyes of this elderly drunkard noted the form and features of every individual who entered or left by the main door, whilst at the same time he paid the utmost possible attention to the comings and goings of any person who used the passage by the window.

To facilitate his observations in this direction he querulously complained to the waiter that the atmosphere was stuffy, and prevailed on the man to raise the window a few inches, thus admitting a breath of clear cold air.

Brett had previously ascertained from his agent that Gros Jean and his daughter were still in the private part of the building. No other visitor had put in an appearance, and so the time passed, until the clock in the cafÉ marked eleven, without any incident occurring which could be construed as having even a remote bearing upon his quest.

Brett began to feel that his diligence that night would not be rewarded.

At five minutes past eleven, however, a pink-and-white Frenchman, neatly attired, unobtrusive both in manner and deportment, entered the cafÉ and seated himself quietly near the door. He ordered some coffee and cognac, and lighted a cigarette.

The barrister, of course, took heed of him as of all others, and he would soon have placed him in the general category that merited no special attention had he not noticed that the newcomer more than once glanced at the clock and then towards the corner bar, whence, it will be remembered, a small door led towards the billiard saloon in which La Belle Chasseuse had displayed her prowess with the pistol.

In such a community the stranger's self-possession and reticence were distinguishable characteristics. So Brett watched him, largely for want of better occupation.

"That is a man of unusual power," was his summing up. "He is elegant, fascinating, unscrupulous. Although apparently out of his natural element in this neighbourhood, he has some purpose in putting in an appearance in such a place as this at a late hour. Perhaps he is one of mademoiselle's lovers, though he looks the sort of person who would be singularly cool in conducting affairs of the heart, and most unlikely to wait many minutes beyond the time fixed for an appointment. His hands are large and sinewy, his wrists square, and, although slight in physique, I should credit him with possessing considerable strength. Being a Frenchman, he should be an expert with the foils. The effeminate aspect given to his face by his remarkable complexion might easily deceive one as to his real character. As a matter of fact, he is the only unusual man I have seen during my two hours' lounge in this corner."

Brett had hardly concluded this casual analysis of the person who had enlisted his close observation, when the private door into the bar opened and Mlle. Beaucaire entered.

Without taking the least notice of any of the numerous occupants of the cafÉ she turned her back on them, and apparently busied herself in checking the contents of the cash register. Beyond this useful instrument was a mirror, and Brett at once perceived that from the point where she stood she could command a distinct reflection of the pink-and-white Frenchman.

The latter was gazing at the clock, and whilst doing so stroked his chin three times with his right hand. Immediately afterwards La Belle Chasseuse three times rang the bell of the register, and then, having apparently concluded her inspection, quitted the bar as unceremoniously as she had entered. Half a minute later the Frenchman finished the remains of his cognac, lit another cigarette, and passed into the street.

It was with difficulty that Brett restrained himself from following him, but he was certain that no one could leave the residential portion of the building without using the passage—a view of which he commanded from his window—and he resolutely resolved to devote himself for that night to shadowing the movements of the ex-circus lady.

His patience and self-denial were soon rewarded. A light quick step sounded in the passage, and a shrouded female form shot past the open window.

Then the inebriated individual, now hopelessly muddled by drink, staggered towards the door and lurched wildly round the corner, just in time to see mademoiselle cross the Boulevard and daintily make her way between the rows of stalls.

The air seemed, however, to have a surprising effect on the old reprobate, for the simple reason that to simulate drunkenness and at the same time keep pace with the lady's rapid strides was out of the question.

La Belle Chasseuse was evidently in a hurry. She sped along at a surprising pace, until she reached a crossing where the rows of stalls and booths were temporarily suspended. At one corner stood a cab, and towards this vehicle she directed her steps. Before Brett quite realized what was happening, the door of the cab opened, mademoiselle jumped inside, and, as if he were waiting for her appearance, the driver whipped up his horse and drove off at a furious pace.

At that instant a small victoria with a sturdy pony in the shafts, which had just deposited a lively fare in the vicinity of the Moulin Rouge, drove along the street.

Brett sprang into it and said eagerly to the driver—

"Keep that cab in sight! I will pay you double fare!"

The man tightened his reins and raised his whip in prompt obedience to the order, when suddenly two men jumped into the vehicle from opposite sides, seized Brett and forced him down on to the seat, whilst one of them said in stern tones to the astonished cabby—

"Take us at once to the Central Prefecture of Police."

The man recognized that these newcomers were not to be trifled with. Without a word or a question, he rattled his horse across the stone pavement, and Brett, choking with rage at this interference at a supreme moment, realized that for some extraordinary reason he was a prisoner, and in the hands of a couple of detectives.

By this time the cab containing the lady had vanished, but the barrister made one despairing effort.

"For heaven's sake," he said to his captors, "take me where you will, but first follow that cab and ascertain its destination."

"What cab?" demanded one of his guards sarcastically.

"The cab which I wished our driver to overtake at the moment when you pounced on me."

"This is a mere trick," broke in the other. "Don't bother about his cab. We have got him safe enough, and let the commissaire deal with him now."

"Listen to me," cried Brett. "You are making a frightful mistake. Your action at this moment may cause irretrievable delay and loss. If you will only do as I tell you——"

"Shut up," growled the first man, "or it will be worse for you. Your best plan, my good fellow, is to keep a quiet tongue in your head."

It was not often that Brett lost his temper, but most certainly he lost it on this occasion. He was endowed with no small share of physical strength, and for an instant the wild notion came into his head that he might perhaps succeed in throwing the two detectives into the roadway and then overpower the driver, taking charge of the vehicle himself and trusting to luck to again catch sight of the vanished lady and her companion, who, he doubted not, had awaited her arrival at the quiet corner where she joined him.

Unconsciously he must have given some premonition of this desperate scheme, for the two policemen tightened their grasp, forced his hands higher up his back, and bent his head forward until he was in danger of having either his neck or his shoulder dislocated.

"Will you keep quiet?" murmured the chief detective. "You cannot escape, and you are only making the affair more disastrous to yourself."

Then Brett realized that further resistance was hopeless. He managed to gurgle out that if they would allow him to assume a more comfortable attitude he would not trouble them any further.

Gingerly and cautiously the two men somewhat relaxed the strain, and he was able to breathe freely once more.

Then he laughed, almost hysterically, but he could not help saying in English—

"The shadow of Scotland Yard falls on me even here. Poor old Winter, how I will roast him over this adventure!"

"What are you talking about?" demanded one of the men.

"I was only thinking aloud," replied Brett.

"And what were your thoughts?"

"Simply this, that the sooner I meet your remarkably astute commissary the better I shall be pleased."