"This: a sort of small howitzer--I think of Krupp's manufacture, but you would be better able to judge than I--is mounted on the platform of the tower! I examined it, Mr. Addison, last night, and like a fool concluded that it had been used at some time for a local celebration and never dismounted! It was trained--as I remembered nearly too late--and laid at a certain elevation in such a way that it was evidently never meant to be moved. Yet at the time the significance of this did not strike me. How the range was found so exactly we shall probably never know; but the truth suddenly burst upon me as you made off through the bushes and as Dr. Damar Greefe came out and began to peer through his gla.s.ses--that it was mechanically set in such a manner that it could drop a projectile into the window above the porch of the Abbey Inn!"

"Good G.o.d! It's hardly credible!"

"It isn't, I admit. But weather conditions favored him; there wasn't a breath of wind. And that he succeeded is proved by the fact that at the present moment your room below is probably still full of poison gas! Of course, it _may_ not have been a gas-sh.e.l.l; he may have relied, as well he might do, on the burst! But I'm taking no chances.

You can well imagine that failing a knowledge of the arrangement on the tower, no explanation of the mystery would ever have been found! A thunder-bolt would be the popular theory, and if any fragments of sh.e.l.l were found who would ever know from where it had been fired?"

"Gatton," I said, "I owe you my life. But why did this fiend try to murder me?"

Gatton smiled.

"I have a theory, Mr. Addison," he replied, "and it is this: I believe he thought that the indiscretion of a certain mysterious lady would bring about his ruin. If I am not mistaken, she has already gone far to put his neck in a halter; and he was determined to nip this latest adventure in the bud by removing the object of her--"

I felt myself changing color, and:

"For heaven's sake say no more!" I interrupted. "It is a gruesome and horrible thought! Yet, perhaps you are right. What must we do, Gatton?

These people have rendered the neighborhood uninhabitable for themselves, now, and--"

Dimly to my ears came the sound of a gun-shot.

"And have fled!" cried Gatton, springing up. "Quick! we must chance the gas!"

"Why? What was that shot?"

"A signal! Dr. Damar Greefe and 'the cat' have escaped!"

He raced out across the landing, amid a chorus of frightened inquiries from the inn staff. I followed him into a front room, and:

"This comes of turning my attention elsewhere for half an hour!" he cried angrily. "I seem to be cursed with fools for a.s.sistants!"

Throwing up the window, he leaned out. I stood at his elbow; and as I looked I saw a great red glow rising from the distant woods. The sound of a car approaching at headlong speed reached my ears, and at the same moment I saw the headlights.

"Hullo, there!" cried Gatton. "Blythe! Petersham!"

The car stopped, and a cry came back:

"We've lost him, sir!... and the Bell House is in flames!"

CHAPTER XXI

IN LONDON AGAIN

"Then the sudden change in the police att.i.tude towards Eric," said Isobel, "is not due to any discoveries which you or Inspector Gatton have made at Friar's Park?"

"That I cannot say," I replied. "We have made certain discoveries as I have already told you, but whilst they distinctly point to some criminal whose ident.i.ty is not yet fully established, unfortunately I cannot say that in a legal sense they clear Coverly."

Isobel, as I had thought at the first moment of our meeting, looked very tired and had that pathetic expression of appeal in her eyes which had hurt me so much when first it had appeared there on the morning after the tragedy. She was palpably ill at ease, and I had small cause to wonder at this. Although a veiled paragraph (in which I thought I could detect the hand of Gatton) had appeared in the press on the previous day, briefly stating that evidence had been volunteered by Sir Eric Coverly which had led to an entirely new line of police inquiry, the item of news--which had naturally excited wide-spread interest--had never been amplified. Amid the alarms and excursions which had terminated my visit to Upper Crossleys, Gatton I supposed had forgotten to refer to this matter; but I did not doubt that the paragraph was an inspired one issued from Scotland Yard.

My friend's object in circulating this statement was not by any means evident to me, but as I expected to see him later that day I hoped to be able to obtain from him some explanation of his new tactics.

Many hours had elapsed since, with the flames of the burning Bell House reddening the night behind me, and throwing into lurid relief the fir-groves surrounding Dr. Damar Greefe's mysterious stronghold, I had been borne along the road towards London. That Gatton had hoped for much from a detailed search of the Eurasian's establishment, I knew, for I had not forgotten his anger at the appearance of the flames above the tree tops which had told of the foiling of his plans.

Under cover of the conflagration the cunning Eurasian had escaped.

Every possible means had been taken to intercept him, and whilst Gatton, inspired by I know not what hopes, had hastened to the burning Bell House, I had set out in the police car in pursuit of Dr. Damar Greefe accompanied by Detective-Sergeant Blythe--upon whom, apparently, the onus of the fiasco rested.

In despite of these measures, the hunted man had made good his retreat; and Blythe and I had entered the outskirts of London without once sighting the car in which Dannar Greefe had fled.

No communication reached me on the following morning, and I found myself, consumed with impatient curiosity, temporarily out of touch with Gatton. Then, shortly after mid-day, came a telegram:

"Endeavor induce Sir Eric come to your house eight to-night. Will meet him there. Gatton."

Welcoming any ground for action--since to remain pa.s.sive at such a time was torture--I called at once at Coverly's chambers. He was out.

But I left an urgent written message for him, and in the hope of finding him with Isobel, hurried to her flat. He had not been there that day, however; and now I could only hope that he would return to his rooms in time to keep the appointment. For that Gatton had some good reason for suggesting the meeting I did not doubt.

Gatton and I were now agreed that Dr. Damar Greefe, if not directly responsible for the death of Sir Marcus, at least had been an accessory to his murder. At any rate he had shown his hand; firstly, in the attempted a.s.sault upon myself by his Nubian servant and secondly, by the devilish device whereby he had propelled some sort of gas projectile (for this we now knew it to have been) from the tower of Friar's Park into my room at the Abbey Inn. I had, then, become obnoxious to him; he evidently regarded my continued existence as a menace to his own.

Two explanations of his att.i.tude presented themselves: one, that my inquiries had led me daily nearer to the heart of the mystery; or, two, that the doctor's mysterious a.s.sociate, the possessor of the green eyes, had adopted an att.i.tude towards myself which the Eurasian had counted sooner or later as certain to compromise him. In short, whilst it was sufficiently evident to me that these mysterious people residing at Upper Crossleys were the criminals for whom New Scotland Yard was searching, no definite link between their admittedly dangerous activities and the crime we sought to unravel, had yet been brought to light.

On the other hand, whilst it was not feasible to suppose that any relationship existed between Sir Eric, the new baronet, and the Eurasian, or the woman a.s.sociated with the Eurasian, I was quite well aware that, equally, there was no evidence to show that such an a.s.sociation did not exist.

I longed to be able to offer some consolation to Isobel, who at this time was pa.s.sing through days and nights of dreadful apprehension; but beyond imparting to her some of my own personal convictions, I was unable to say honestly that the complicity of Coverly in the murder was definitely and legally disproved.

"If only he would break his absurd silence," she said suddenly. "This ridiculous suspicion which still seems to be entertained in some quarters would be removed of course; but his every act since the night of the tragedy has only intensified it."

She sat facing me on the settee, her hands locked in her lap, and:

"Do you refer to any new act of his," I asked, "with which I am not at present acquainted?"

She nodded slowly.

"Yes," she said; "but I can only tell you in confidence, for it is something which Inspector Gatton does not know."

"Please tell me," I urged; "for you are aware that I have no other object but the clearing of Coverly in the eyes of the police and the public."

"Well," she continued, with hesitation, "last night he lodged with me a copy of a _declaration_ which he a.s.sured me cleared him entirely.

But he imposed an extraordinary condition."

"What was that?" I asked with interest.

"It was only to be used in the event of the worst happening!" she said.

"What do you mean? In the event of his being put on trial for murder?"

Isobel nodded.