"Oh, yes, very often. But he always encloses her letter to me. He never gives his address to her, for fear, I suppose, that it should fall into other hands. I wired to his rooms in Paris a week ago, but, as yet, have received no response. His rooms in London are closed. I was up there on Thursday. Why he keeps them on when he's away for years at a time, I can never understand."

"Probably sub-lets them, as so many fellows do," Farquhar suggested, "yet it's unfortunate we can't get into touch with him."

"Miss Griffin is acquainted with him--I wonder if she knows his whereabouts?" remarked Diamond quite innocently.

"She knows him!" Frank echoed in surprise. "Are you quite sure of that?"

"Quite. She told me so."

"How could she know a man who is admittedly an outsider?" asked Frank.

"My dear Mr Farquhar," he laughed, "your modern girl makes many undesirable acquaintances, especially a pretty go-ahead girl of Miss Griffin's type."

Frank bit his lip. This friendship of Gwen's with the man Mullet annoyed him. What could she possibly know of such a man? He resolved to speak to her about it, and make inquiry into the circ.u.mstances of their acquaintance.

He must warn her to have nothing to do with a man of such evil reputation, he thought. Little did he dream that this very man whom the world denounced as an outsider had stood the girl's best and most devoted friend.

He walked back along the village street to the Manor, and dressed for dinner, his mind full of dark forebodings.

What would be the end? What could it be, except triumph for those enemies, the very names of whom were, with such tantalising persistency, withheld.

Half an hour after he had left the Doctor's cottage the village telegraph-boy handed Aggie a message which she at once carried to her foster-father.

He tore it open, started, read it through several times, and then placed it carefully in the flames.

Then he hurriedly put on his boots, overcoat and hat, and went forth, explaining to his wife that he was suddenly called on urgent business to London.

That evening, just before ten o'clock, a short dark figure could have been seen slinking along by the railings of Berkeley Square, indistinct in the night mist, which, with the dusk, had settled over London.

The man, though he moved constantly up and down to keep himself warm, kept an alert and watchful eye upon the big sombre-looking mansion opposite--the residence, as almost any pa.s.ser-by would have told the stranger, of Sir Felix Challas, the anti-Semitic philanthropist.

Over the semicircular fanlight a light burned brightly, but the inner shutters of the ground floor rooms were closed, while the drawing-room above was lighted.

Time after time the silent watcher pa.s.sed and repa.s.sed the house, taking in every detail with apparent curiosity, yet ever anxious and ever expectant.

The constable standing at the corner of Hill Street eyed the dwarfed man with some suspicion, but on winter nights the London streets, even in the West End, abound with homeless loafers.

The Doctor, wearing a shabby overcoat several sizes too large for him and a felt hat much battered and the worse for wear, watched vigilantly and with much patience.

He saw a taxi-cab drive up before Sir Felix's and a rather tall, good-looking man in opera hat and fur-lined coat descend and enter the house. The cab waited and ten minutes later the visitor--Jim Jannaway it was--was bowed out by the grave-faced old butler, and giving the man directions, was whirled away into Mount Street, out of sight.

"I suppose that's the fellow!" murmured the ugly little man beneath his breath, as he stood back in the darkness against the railings opposite.

Hardly had the words escaped his lips when a hansom came from the direction of Berkeley Street, and pulling up, an old, rather feeble white-bearded man got out, paid the driver, and ascending the steps rang the bell.

He was admitted without question, and the door was closed behind him.

"Erich Haupt, without a doubt," remarked the Doctor aloud. "Why has he returned to London? Has he made a further discovery, I wonder. The description of him is exact."

For half an hour he waited, wondering what was happening within that great mansion.

Then Jim Jannaway suddenly returned, dismissed his "taxi," and was admitted. All that coming and going showed that something was in the wind.

"Red Mullet" had given him due warning from his hiding-place. His telegram had been despatched from Meopham, which he had discovered was a pleasant Kentish village, not far from Gravesend. He was evidently in concealment there.

Just before eleven o'clock another hansom turning out of Hill Street in the mist, pulled up before the house, and he watched a dark figure alight from it.

Notwithstanding the dim light he recognised the visitor in an instant.

The figure was that of a tall, dark-eyed girl.

"Good Heavens!" he gasped, staring across the road, rigid. "Mullet was right! He was not mistaken after all! By Jove--then I know the truth!

We are betrayed into the hands of our enemy!"

And as the Doctor stood there he was entirely unaware that he, in turn, was being watched from the opposite pavement--and by a woman!

CHAPTER TWENTY NINE.

WHICH SOLVES A PROBLEM.

That day had been an eventful one at Pembridge Gardens. Indeed, the event of the great scholar, Arminger Griffin's life had occurred.

It happened in this way. The January morning had been so dark that he had been compelled to use the electric light upon his study table, and during the whole morning he had been engaged upon that same futile task--the problem of the cipher.

With the Hebrew text of Ezekiel open before him, and sheets of ma.n.u.script paper upon the blotting-pad, he had been absorbed for hours in his cabalistic calculations which, to the uninitiated, would convey nothing. They appeared to be elementary sums of addition and subtraction--sums consisting of ordinary numericals combined with letters of the Hebrew alphabet.

And curiously enough, in a back bedroom in the Waldorf Hotel, in Aldwych, the white-bearded old German, Erich Haupt, who only the previous night had returned from the Continent, sat making almost similar calculations. Before him also he had a copy of the Hebrew Bible, and was taking sentences haphazard from Ezekiel xix, the lamentation for the Princes of Israel under the parable of the lion's whelps taken in a pit.

Early in the morning he had rung up Sir Felix on the telephone beside the bed, announcing his arrival, and obtaining an appointment for later in the day.

Both scholars, unknown to each other, were busy upon the same problem, each hoping for success and triumph over the other.

Through weeks and weeks Griffin, seated in his big, silent, rather gloomy study, had tried and tried again, yet always in vain. He was a calm, patient man, knowing well that in cryptography the first element towards success is utmost patience.

It was noon. The fog had not lifted, and Bayswater was plunged in the semi-darkness of the London "pea-souper."

Gwen was out. She was trying on a new evening frock at Whitley's--a dainty creation in pale blue chiffon ordered specially for a dance which Lady Duddington was giving in Grosvenor Street in a few days' time.

Alone, his grey head bent on the zone of shaded light upon the big writing-table, the Professor had ever since breakfast time been putting a new cipher theory to the test.

All the thirty odd numerical ciphers known to the ancients he had applied to certain chapters of the Book of Ezekiel, but each one in vain. The result was mere chaos. The ancients employed numerous methods of cryptography besides the numerical cipher, among them being the use of superfluous words where the correspondents agreed that only some of the words, at equal distances apart, was necessary to form the message; by misplaced words; by vertical and diagonal reading; by artificial word grouping; by transposing the letters; by subst.i.tution of letters; or by counterpart tabulations with changes at every letter in the message, according to a pre-arranged plan.

All these, however, he had, in face of the reading of the sc.r.a.p of the ma.n.u.script of the dead discover of the secret, long ago dismissed.

He held the firm opinion--perhaps formed on account of that crumpled paper found at the Bodleian--that the cipher was a numerical one, and based upon some variation of the numerical value of the "waw" sign, or the number six.

He now fully recognised how very cleverly old Erich Haupt had endeavoured to put him off the scent. The German was a very crafty old fellow, whose several discoveries, though not altogether new, had evoked considerable interest in academic circles in Europe. He was author of several learned studies in the Hebrew text, as well as the renowned work upon the Messianic Prophecies, and without a doubt now that he had possessed himself of the dead professor's discovery he intended to take all the credit to himself. Indeed it was his intention to pose as the actual discoverer.

Continuing his work in silence and without interruption Griffin had been making a long and elaborate calculation when, very soon after the little Sheraton clock upon the mantelshelf had chimed noon, he started up with a cry of surprise and stared across at the long old-fashioned bookcase opposite.

Next moment his head was bent to the paper before him, as he rapidly traced numerals and Hebrew characters, for he wrote the ancient language as swiftly as he wrote English.