such results. Doyou know where Barakoff is now?" he asked in French.

  Regnier shook his head.

  "He was in Moscow a year ago," he replied, "and after that we heard ofhim in Prague, in Rome, and lastly in Madrid, but he disappearedsuddenly and we have not been able to pick up his tracks again. He is ashort, powerful, thickset man with a rather hunched back, but nothingelse peculiar about his appearance."

  Next day, however, Regnier came to the adventurous trio in greatexcitement.

  "Barakoff is in England!" he declared. "We have just had word fromGaston Meunier who saw him in Brighton a week ago!"

  "But how on earth did he get there?" asked Jules. "You know every onehas been looking for him for months past. He could not possibly havegot through by any of the ordinary routes."

  "I'm as puzzled as you are, monsieur," was Regnier's reply.

  "Well, if he is there we'd better go over," said Dick. "Yvette can gowith me in Mohawk II and Jules by the night boat. I shall fly theMohawk to my old shed in Norfolk; I have kept it on in case ofemergency, and it is quite safe."

  An hour later Dick was in close talk with a young Russian named NicholasFedoroff. He had been an active member of a circle of dangerousanarchists in Zurich, but had dropped out and was now living in Paris.By good fortune Dick had saved his baby girl, at imminent risk of hisown life, from being killed by a motor-van in Paris, hence Fedoroff wasimpulsively grateful.

  "Look here, Nicholas," said Dick bluntly. "I want you to tell meanything you can about Barakoff."

  They were seated in a small cafe in the Rue Caumartin, which wasFedoroff's favourite haunt. The Russian glanced round fearfully.

  "Hush!" he said in broken French and in evident horror. "I--I can'ttell you! He has agents everywhere. If I were heard even speaking hisname I should never get home."

  The man's agitation was so pronounced that one or two men in the cafeglanced at him curiously. Dick saw that the mere mention of Barakoff'sname had thrown the Russian completely off his balance.

  "Come to my flat," he said quietly, "you have got to tell me."

  They drove in a taxi to Dick's flat, where a stiff dose of brandy pulledthe Russian together. Yet he still trembled like a leaf.

  "How did you know that I knew Barakoff?" he asked.

  Instantly Dick was keenly on the alert. He had no idea that Fedoroffhad been associated with the notorious criminal; his appeal to Fedoroffhad been a chance shot. Evidently he had stumbled on a matter ofimportance. But he was quick to take advantage of his good luck.

  "Never mind how," he said. "I do know, and that's enough. You have gotto tell me. I believe Barakoff is at the bottom of the trouble inEngland. I know he is there, and I want to know where he is and how hegot there."

  The Russian's agitation increased.

  "You must not ask me; I cannot tell you," he gasped.

  "Then a few words from me in a certain quarter--not the police," Dicksuggested.

  The Russian collapsed.

  "No, no, I will tell you," he moaned. "He is in England, but I don'tknow where. He flew over."

  "Flew over!" echoed Dick in utter amazement. "Nonsense, he couldn'thave got in that way. Every aerodrome in England has been watched formonths."

  "But he did," the Russian asserted. "He has his own aeroplane. Itmakes no noise, and it goes straight up and down."

  Here was a surprise indeed! The secret of the helicopter with itsalmost unlimited power for evil was also in the hands of one of the mostdesperate ruffians in the world! There was indeed no time to be lost.

  Fedoroff could tell Dick little more. What the secret of Barakoff'sinfluence over him was Dick could not fathom. He would say nothing, butevidently was in deadly fear.

  One little item Dick did indeed extract and it was to prove valuable.Fedoroff knew that Barakoff had associates in Soho. And that was theonly clue they could gain to his possible whereabouts.

  That evening Dick, Yvette, and Jules crossed to England, and withofficial introductions from Regnier, Dick lost no time in getting intocommunication with Detective Inspector Buckhurst, one of the ablest menof Scotland Yard's famous "Special Department," a man whose knowledge ofthe alien scum which infested London was unrivalled. To him Dick toldall he knew.

  Buckhurst looked grave.

  "I know of the man, of course," he said, "but I have never seen him andI don't think any of my men have. We have combed Soho out prettythoroughly, but no one answering to Barakoff's description has beenseen."

  The position was very grave. If Fedoroff's information was correct--andDick saw no reason to doubt it--here was a desperate scoundrel lurkingin England armed with an aeroplane of unknown design and power, and inpossession of a terrible secret which, unless his career was brought toan end, threatened the entire population of the country. But where washe hiding, and, above all, where was his machine? Could it possibly behidden, Dick wondered, in the very heart of London? The idea was almostincredible, but Dick knew Barakoff's undoubted genius and his amazingdaring.

  A remarkable feature of Yvette's personality was her wonderful influenceover children. They seemed literally to worship her. She would getinto conversation with the half-tamed _gamins_ of the streets and in afew hours they would be her devoted slaves. She now proceeded to enlistthe ragged battalions of Soho in a fashion that caused Buckhurst muchamusement.

  "Find out for me all the hunchbacked men you can," was all theinstructions she gave them.

  "But, mademoiselle," said Inspector Buckhurst, "it will be the talk ofSoho, and our man if he is there will slip away."

  Yvette was unmoved.

  "Just think a minute," she said. "Who can go about all day and allnight without being suspected? The children. Who can go into denswhere your men hardly dare to venture? The children. Who know all thehidden haunts of which your men are utterly ignorant? The children.And finally, who are the most secretive people in the world? Again thechildren. Do not fear, Monsieur Buckhurst, they will not talk exceptamong themselves, and that will do no harm."

  Buckhurst was far from satisfied, but he had gained such a respect forYvette that he did not venture to override her. At the same time, hetold her plainly that he should keep his own men busy. Yvette onlylaughed.

  During the next forty-eight hours dozens of hunchbacked men werereported. Many of them were people whom not even the police knew. Theywere, of course, mostly harmless, but Buckhurst opened his eyes when oneof them proved to be a notorious forger for whom the police had beenlooking for some months, and who had all the time been hidden undertheir very noses! Buckhurst began to feel a growing respect for theamazing French girl, who had beaten his smartest detectives on their ownground. But, unfortunately, none of the hunchbacks was the man theywanted, and at last they began to suspect that Fedoroff's informationwas at fault.

  Then came a dramatic surprise. One of Yvette's small assistants, asharp little Polish Jew boy, came to her with a strange story. He hadbeen wandering about the night before and had seen a hunchbacked man lethimself out of the side door of a big building half-way between GreekStreet and War dour Street. The man had walked a considerable distancein a northerly direction into a part of London the boy did not know atall, and had entered an unoccupied house, stayed a few minutes, and comeout again. The lad had shadowed him all the way, and had followed himhomewards, until he again entered the building in Soho.

  Dick, Jules, and Yvette turned out at once. The boy pointed out thebuilding to them. It was a tall structure which dominated all theothers in the vicinity. It was apparently a big shop with storeroomsabove. On the facia over the windows was the name "Marcel Deloitte,Antique Furniture." There was nothing to indicate that it differed inthe slightest degree from dozens of other shops and buildings in theneighbourhood. Yet Dick felt suspicious.

  "We can do nothing till I get the Mohawk handy," said Dick. "I willbring her down to-night."

  And he paused.

  "I wish you would keep out of this, Yv
ette," he went on wistfully. "Itis going to be very dangerous, I am convinced." The French girl wasgrowing very dear to him, and he shuddered at the idea of her beingmixed up in the coming struggle with a desperado of Barakoff's type.

  But Yvette shook her head.

  "I'm in this to the finish, Dick," was all she said in her pretty brokenEnglish, and Dick knew he could not move her. But he was full of fear.

  That afternoon another explosion of the pale-violet vapour occurred inNorth London not far from Finsbury Park Station. Dick rushed to thespot with the boy who had followed the hunchbacked man, and the ladrecognised the place without hesitation. The house destroyed was, hewas confident,