lifewould be worth hardly a moment's purchase.

  But he knew it was useless to remonstrate. Yvette had a perfect geniusfor "make-up," and what was far more important, a perfect knowledge ofthe strange _argot_ which served the underworld of Paris. Jules wasalmost as clever as Yvette. But in this particular, of course, Dick wasfar behind. He could not hope to sustain his part in surroundings wherea single wrong word would mean instant suspicion, and probably a swiftand violent death for all three.

  "I wish I could go with you, Yvette," he said wistfully, "but, alas! Iknow it is quite impossible."

  Yvette had many friends in the lower quarters of the Montmartre. Theproprietors of many of the low _buvettes_ of the slums--places where onecould get absinthe and drugs--were secretly in her pay, and so far asthey were concerned she had no fears; the traffickers trusted herbecause they knew their secrets were safe. And by an ingenious codesystem which depended upon a mere vocal inflexion of certain commonwords she could reveal her identity, no matter what her disguise, tothose who were in her secret.

  Darkness had fallen upon the city when two appalling specimens of theworst vagabondage of Paris--a man and a woman--crept silently throughthe market quarter towards one of Paris's vilest haunts of villainy.They were such woebegone specimens of humanity as might have served forfigures in some new "Inferno." Bedraggled and unkempt, their hands andfaces besmirched with grime, their clothes hanging in tatters, it wouldhave been impossible for even the keenest eye to have detected the smartFrench girl and her usually debonair brother. So far as appearanceswent they were safe enough. The risk would come when they began totalk, and especially when they began to ask questions. Here a slip ofthe tongue might betray them. But the risk had to be taken.

  The Prefet himself, quite as anxious as Dick for the safety of Yvetteand Jules, had taken precautions to protect them as far as possible.Actual escort, of course, was out of the question. Both Yvette andJules carried revolvers, but in addition Jules had concealed in theample pockets of his villainous clothing, a tiny but delicate wirelesstelegraph apparatus, powerful enough upon a dry battery to send out awireless wave which would carry a thousand yards or so.

  This dainty little bit of electrical work was the invention of DickManton. Hardly larger than an old-fashioned watch it was operated by ahundred-volt battery which fitted into a specially made pocket, and thetiny transmitting key could be operated with one finger without arousingthe slightest suspicion. Gregoire's agents were dotted thickly aroundthe unsavoury neighbourhood, each in touch, by means of the wireless,with every movement Yvette and Jules might make. Dick himself was notfar away. How amply these precautions were justified the events of thenight were to show.

  For hour after hour Yvette and Jules slunk from one haunt of vice toanother, always keenly on the alert, frequently helped by one or anotherof Yvette's disreputable friends, but yet unable to pick up theslightest vestige of the trail of which they were in such active search.

  At length their patient vigil culminated.

  Plunging deeper and deeper into the labyrinth of the slums, they hadpenetrated at length to a tiny bar in the very lowest and most dangerousportion of the market section. The place was crowded with a mass ofriff-raff at which even Yvette and Jules, accustomed as they were tosuch sights and sounds, could not repress a shudder.

  The proprietor, as it happened, was a beetle-browed Provencal whose oneredeeming feature was gratitude to Yvette. His character was utterlybad and he had been mixed up in dozens of affairs more or lessdisreputable. A year or two before a serious charge of which hehappened to be innocent had been brought against him. Yvette hadmanaged, with considerable trouble, to lay the real culprit by theheels, and Jules Charetier, Apache though he was, would now go throughfire and water to serve her. Yvette knew that in his house she waspersonally far safer than she would have been in many more pretentiousestablishments.

  Charetier raised his eyebrows when he caught the slight inflexion thatinstantly revealed to him Yvette's identity. But he took no furthernotice beyond serving the drinks for which she had asked.

  A moment later, with a significant look, he quitted the room. Yvette,with a slang caution to look after her drink for a moment, slipped intothe filthy street and round the corner to the side entrance of thehouse. Charetier was waiting for her, and a few moments later they wereseated in the man's dingy room on the floor above the bar.

  "Whatever are you doing here, mademoiselle?" Jules burst outimpulsively. "This is no place, even for you!"

  "Listen, Charetier," replied the girl rapidly. "Something is brewingfor next Friday. Something serious! You have seen the posters. I_must_ find out about it. Can you tell me where any of the `Seven' areto-night?"

  Jules Charetier paled at the mention of "The Seven," the powerfulcamarilla whose hidden influence was felt throughout the criminalunderworld of Paris, London, and New York. The men who, practicallywithout risk to themselves, were responsible for half the anarchistcrimes of the three great capitals. Who they were, and their realnames, not even Yvette knew. Never appearing directly themselves, theyworked entirely through agents, and fighting against them, the policefound themselves in a stifling fog of mystery. But, as Yvette knew,Charetier was deep in the councils of Continental Anarchism, and sheknew, too, that in his hands the life of the ordinary police agent wouldhave been worth nothing. Even for herself she was not very confident,but she had decided on a bold stroke, trusting Charetier with everythingon the ground of the service she had done him.

  At first the man was obdurate.

  "Not even for you, my dear mademoiselle," he said sullenly. "But,mademoiselle," he went on earnestly, "we have been friends, therefore Iimplore you for your own sake to drop the matter and get away asspeedily as possible. I cannot tell you anything."

  Yvette's revolver flashed out and in an instant she had the innkeepercovered.

  "Listen, Jules!" she cried imperiously. "My brother is below, and thehouse is surrounded. If I stamp upon the floor you will be raidedinstantly. And you know there are things here you would not like thepolice to see--they don't know it, but you and I do! Suppose Demidofflearned that his papers had fallen into Raoul Gregoire's hands--eh?"

  For a moment Yvette thought Charetier would have risked everything andsprung at her. But it was only for a moment. Then he collapsed. Itwas evident he feared Demidoff, the notorious Bolshevik agent, even morethan he feared the police.

  "Very well, mademoiselle," he replied, beads of perspiration standingout upon his wide white forehead and, despite his bravado, a hunted lookcrept into his eyes. "You might try the `Chat Mort.' There will be ameeting there at three o'clock this morning. But again I implore younot to go. You cannot get in and if you did you would never come outalive."

  "In which room do they meet?" was Yvette's only reply.

  "The one at the back, looking out upon the old courtyard," wasCharetier's reply. "I know no more than that."

  "Thanks, Charetier," said Yvette as she rose to go.

  "But, my dear mademoiselle," implored the innkeeper, "you will notbreathe--"

  Yvette cut him short.

  "That's enough, Charetier," she said in a freezing tone. "You surelyknow you are safe so far as I am concerned. You have done me a greatservice to-night and I shall not forget." Five minutes later Yvette andJules were hastening to the "Chat Mort," a tavern of a gayer night-lifethan the one they had just quitted. It stood on the corner of twofilthy slums in the Villette Quarter and at the rear was one of thosetiny courtyards which so often go with old French houses--a place givenover to the storage of odds and ends of flotsam and jetsam which arehardly worth the trouble of keeping, or even stealing. Only a ricketywooden fence divided it from the horrible alley deep in mud and refuse.

  They realised at once that to enter the house would be impossible. Itwas now long past two o'clock and the street was deserted; everythingwas silent as the grave, and from the closely shuttered "Chat Mort"there was not a glimmer of light. T
o all appearances the inhabitantswere soundly asleep.

  But Yvette placed implicit trust in Charetier. She was sure that themysterious meeting would be held at the appointed hour.

  They crept silently to the rear of the building, cautiously forced a waythrough the crazy fence, and a moment later were outside the window ofthe room which Charetier had indicated as the meeting-place.

  Crouching beneath the window they listened intently. They were safeenough except for some unforeseeable accident.

  There was no sound in the room; no glimmer of light through theshutters.

  Jules took from his pocket a tiny drill which speedily and silently bita half-inch hole through the rotting woodwork of the window. Into thishe thrust a plug which at the end bore an extremely