poison-fiend began to come back to him.

  Then came the critical moment. Five hundred yards ahead and a thousandfeet below, Barakoff, close to the ground, must rise soon to gain theelevation he required.

  That was the moment for which Dick had been waiting. He called on hismachine for the last ounce of effort he had been holding in reserve.

  The Mohawk shot forward. A few seconds later Dick was directly abovethe Russian. So far as air tactics went he had won; the Russian wasentirely at his mercy.

  Then began surely the strangest aerial combat ever witnessed. To andfro the machines dodged, Barakoff striving to gain height and succeedingfor a moment only to find his pursuer above him again and bulletswhining round him; Dick striving to force the Russian down to the groundwhere he must either land or crash. For fully half an hour the machinesflitted backwards and forwards around the town of Ashford. Dick had nofear of the result; his only risk was whether he could send Barakoffdown before dusk came. Unless he could do this there was every dangerthat the Russian would escape under cover of darkness.

  At last the end came.

  Dick had forced his antagonist so low that, as a last desperate resort,Barakoff had to leap upward to clear a big group of elms. Hemiscalculated by a few feet, his machine touched the upper branches andwent smashing to earth. Three minutes later Dick was standing besidethe body of the death-dealer.

  Barakoff's machine was a complete wreck and was blazing furiously. Theman himself had been flung clear and lay in a crumpled heap, stone dead.

  There is little more to tell.

  The formula for the powder with which the bomb was charged was found inBarakoff's laboratory, and with it, in Russian, a prescription which, onbeing tested, proved to be a complete cure for the disease. It wasfound just in time to save those who would otherwise have been thevictims of the explosion at Finsbury Park.

  It was evident that Barakoff must have maintained his laboratory in Sohofor months. Obviously the manager of the shop was one of hisaccomplices, and apparently he had recognised Yvette and deliberatelythrown her into Barakoff's hands. Then realising that discovery wasinevitable he had slipped out of the building, probably by a window asneither of the assistants had noticed him leave. He was never found.The assistants themselves proved to be respectable young fellows who hadbeen employed only a few weeks and who clearly knew nothing of thenefarious conspiracy.

  Nothing but the Mohawk had prevented Barakoff's escape! And Dick Mantonreceived later on the official thanks of the British Government for hisdaring exploit.

  CHAPTER FIVE.

  THE MASTER ATOM.

  "Oh! la la! How horribly dull life is! I do wish something reallystartling would happen, Dick!"

  The words were spoken in pretty broken English by Yvette Pasquet, who,charming and _chic_, as usual, was sitting with Jules and Dick Manton.The adventurous trio were dining _al fresco_ in the leafy garden of theold-world "Hotel de France" on the river bank at Montigny, thatdelightful spot on the outskirts of the great Forest of Fontainebleau, aspot beloved by all the artists and _litterateurs_ of Paris.

  "Something will happen suddenly, no doubt," Dick laughed, glancing athis beloved. "It always does!"

  "I sincerely hope it will," declared Jules in good English. "We'rereally getting rather rusty. I met Regnier yesterday out at Pre Catalanwith Madame Sohet, and he hinted to me that some great mystery hadarisen; but he would tell me nothing further."

  "Regnier, as head of the Service, is always well informed, and like anoyster," Yvette remarked with a laugh. "So I suppose we must wait forsomething to happen. I hate to be idle."

  "Yes. Something will surely happen very shortly," said Dick. "I have acurious intuition that we shall very soon be away again on anothermission. My intuition never fails me."

  Dick Manton's words were prophetic, for on that same evening before ameeting of the Royal Society in London, Professor Rudford, theworld-famed scientist, made an amazing speech in which he said:

  "Could we but solve the problem of releasing and controlling the mightyforces locked up in this piece of chalk, we should have power enough todrive the biggest liner to New York and back. We should have at ourdisposal energy unlimited. The daily work of the world would be reducedto a few minutes' tending of automatic machinery. And, I may add, thefirst nation to solve that problem will have the entire world at itsmercy. For no nation, or combination of nations, could stand evenagainst a small people armed with force unlimited and terrible. And--gentlemen--_we are on the way to solving that problem_!"

  As the words fell slowly and calmly from his lips his hearers felt athrill of ungovernable emotion, almost of apprehension. For they knewwell that he spoke only of what he knew, and the measured phrasesconjured up in their keen brains not only a picture of a world wherelabour had been reduced to the vanishing point, but of a world whereevil still strove with good, where the enemies of society still stroveagainst the established order of things which they hated, where crime inthe hands of the master criminal, armed with force whose potentialitythey could only dream of, would be something transcending in sheerhorror all the past experiences of tortured humanity.

  Supposing the great secret _fell into the wrong hands_!

  The speech at the Royal Society was a nine days' wonder.

  The unthinking Press made merry in the bare idea of a lump of chalkbeing a source of power. Then the transient impression faded as publicattention returned to football and the latest prize-fight. But behindthe scenes, in a hundred laboratories, students bent unceasingly overtheir myriad experiments, striving to wrest from Nature her greatestsecret, the mystery of the mighty energy of the atom. Since the daywhen Madame Curie had discovered that in breaking up, yet seeminglynever growing less, radium was shooting off day and night power whichnever seemed to diminish, the minds of the men of science had beenfilled with the dream of discovering the secret.

  Could they learn to accelerate the process? Could they induce radium todeliver in a few moments the power which, expending itself for centuriesuntold, never seemed to grow less? Could they learn to control it, orwould it, when at last the secret was discovered, prove to be aFrankenstein monster of titanic power, wreaking untold destruction onthe world?

  A thin, keen-faced man sat facing the British Prime Minister in hisprivate room in Downing Street a few days later. This was ClintonScott, one of the smartest men of the British Secret Service, a man ofwide culture and uncanny knowledge of the underworld of internationalcrime. His profession was the detection of crime; his hobby science inany form.

  "We have very disturbing news, Scott," said the Prime Minister, "and Ihave sent for you because the problem before us is largely of ascientific nature and I know all about your hobby."

  Clinton Scott smiled.

  "You are aware, of course, of the latest developments in the search forsome method of releasing and controlling atomic forces," went on thePrime Minister. "I do not profess to understand them deeply myself, butI have a general idea of what is being done and what success wouldimply. Professor Rudford, to whom I applied for information on thesubject, tells me that such a discovery would revolutionise worldconditions. You will understand of your own knowledge all that itimplies, and that is why I have sent specially for you in this matter."

  "I am at the country's service," replied Scott.

  "Now information we have received from Norway suggests very stronglythat the problem has been solved," the other said. "We have nodetails--nothing in fact very definite at all. But it is certain thatsome very queer things have been happening. And from what ProfessorRudford tells me I am assured that we cannot afford to neglect them.Our ordinary men are useless for this kind of thing. Men with aconsiderable knowledge of scientific subjects are absolutely necessary.Otherwise matter which, properly understood, would be full ofsignificance will be passed over as of no account and quite minor andunessential incidents will be followed up, and there would be seriouswaste of time. And time is valuable."


  "I agree that it is," was the terse reply.

  "I want you to go to Norway and look into the matter," the PrimeMinister went on. "Of course I will see that you get all theinformation we have, and you can select your own assistants."

  Clinton Scott suddenly looked grave.

  "Is it known at all?" he asked. "Who is behind this--I mean who hasmade this discovery? You will appreciate my reason for asking. If itis the work of a genuine man of science there would be no immediatedanger, though of course such an invention would upset all ideas ofinternational relations. It is literally true, as no doubt ProfessorRudford will have told you, that the nation in exclusive possession ofsuch a secret could dominate the world. But there are one or two men inthe world who, with such a secret in their possession, would be a realperil to civilisation."

  "Do you