What the speaker meant was evident. He had brought a consignment of petrol to this lonely spot, and his words referred to what I saw around me.

I realized also the significance of what Father Abraham had said to me during his midnight visit. Evidently he knew what the cave contained when he said that I was standing on a powder magazine. According to my calculations it was almost immediately under my little wooden hut. When I had asked him whether he spoke figuratively or literally, he had replied, "Both."

I remembered, too, the article I had seen in the London newspaper. The writer of this article had asked where the Germans had been able to obtain the petrol which enabled them to do their devilish work by means of submarines. Now it was plain. This cave, curiously hidden in the rocky cliff in a quiet, far-away spot on the Cornish coast, suited their purpose admirably. I myself had visited the outer cave on more than one occasion and yet had not discovered it. How many lives, I wondered, had been lost by the stuff which had been stored in this place! I called to mind the times when I had seen phantom-like boats coming round the headland. I remembered how I had puzzled as to what they might mean. Now all was plain; this rocky cliff, although far away from the centre of operations, was important beyond words. Evidently those who had been engaged in this work had cleverly avoided the coast watchers. Quietly and unsuspectingly they had brought cargo after cargo, and when the submarines had need of petrol they had been able to supply them.

All this flashed through my mind in a second, then the match by means of which I had made my discovery went out. I realized the awful danger by which I was surrounded; doubtless all these cans were carefully sealed, yet I knew that one spark might ignite this highly combustible fluid, and I should be burnt to death. But that was the smallest part of my danger. I knew that the men who were engaged in this work would stop at nothing; that the spies who had sought out this lonely cave would be ready to do anything in order to keep a secret.

A hundred wild fancies surged through my brain. I saw now why Father Abraham had been driven from his hut. What his connections with the Germans were I had no idea, but evidently he had been regarded as dangerous to their plans. That, doubtless, was the reason why the old man had warned me. His words came flashing back to my mind, and revealed to me the fact that I had been under constant surveillance. Then I thought of the man and woman who had lately visited me. What was the meaning of their interest in me? Were they what they pretended, or had they some sinister motive in asking me questions?

My discovery made the necessity of action imperative. But what could I do? Here was I, a poor invalid, and, if Dr. Rhomboid was right, I had only a few weeks longer to live. I had, as it seemed to me, only kept myself alive by my strong will power and determination that I would not yield to death. But what could I do? I had by this time learnt something of the police officials in the neighborhood, and I knew how utterly incapable they were of dealing with the matter. I was acquainted with some magistrates in the district, but I feared to go to them; a man like Squire Treherne would be utterly incapable of dealing with such a delicate situation. I knew that in his blunt, straightforward, honest way he would muddle everything. It is true I might write to the War Office or to the Admiralty, but, rightly or wrongly, I did not form a high estimate of their way of doing things; and yet I could see nothing else for it. Even now I might be watched. Even now German agents might be waiting outside the cave to pounce upon me.

I lit another match, and saw something which had hitherto escaped my notice. It was a slip of paper. I s.n.a.t.c.hed at it eagerly and carefully read it, my heart beating wildly all the time.

The light again went out.

How long I remained there in the darkness I do not know, but it seemed to me as though I lived years in a few minutes.

A wild scheme flashed through my brain. I would deal with this matter alone! I could not fight for my country, but I would serve it in my own way.

I listened intently, but could hear nothing save the dull monotone of the waves outside. No whispering voices reached me. The darkness of the cave seemed to intensify the silence. I crept into the outer cave and again listened; still all was silent. Then I made my way into the daylight, taking every precaution before doing so. No, as far as I could tell no curious eyes were watching me. I was alone.

XXIII

A CLUE TO THE MYSTERY

I seemed to have a fresh lease of life as I clambered up the rocky cliff towards my hut. I had no sense of weariness or weakness at all; it might seem as though all my fears had been groundless, and that Dr. Rhomboid had been utterly mistaken.

I expect this was because of the great excitement under which I labored.

Every nerve in my body was in tension; at that moment nothing seemed impossible to me. My mind, I remember, seemed as vigorous as my body, and I felt as though I was walking on air. The possibilities of what I had discovered might mean putting an end to one of the greatest dangers which had been threatening our country. From what I could judge, this might be one of the princ.i.p.al store places of petrol. I realized, as I had never realized before, the cleverness of the German mind. No one, I imagined, would think of this out-of-the-way district as a possible centre of their operations. Naturally the whole of the East Coast from Dover to the extreme North of Scotland would be watched with the greatest care; but who would have thought they would choose this out-of-the-way spot on the North of Cornwall? It might seem as though Providence had led me thither.

More than once on my way to the house did I stop and look eagerly around me, but I was always a.s.sured that no one watched me, and that I was utterly alone; besides, I could not have chosen a more perfect day for my investigation. Although it was now near noon and the weather showed signs of breaking, a thick damp mist still enveloped the whole countryside, thus making observation from a distance almost impossible.

"Everything all right, sir?" asked Simpson, as I entered the house.

"What should be wrong?" was my reply.

"Nothing, sir, only you might have seen a ghost; you look terribly strange and excited, sir."

I laughed aloud.

"I have not felt so well for months, Simpson."

He looked at me dubiously, I thought, and seemed anything but satisfied.

"Are you ready for your lunch, sir?"

"Lunch?" I replied. "Haven't I had lunch?"

Making my way into my little bedroom, I caught a glimpse of my face. I hardly recognized myself! Pale as I had always been since my illness, my pallor had been nothing to the white, drawn, haggard face which I saw in the gla.s.s. But for the wild glitter in my eyes, it might have been the face of a dead man, and yet every particle of my being seemed instinct with life.

After pretending to eat some of the lunch which Simpson had prepared for me, an unusual languor crept over me, and throwing myself on the couch, I quickly fell asleep.

I was awakened by a sound of voices at the door, and I started up quickly. As far as I could judge, I suffered no evil results from the excitement through which I had pa.s.sed. Whatever had caused me unnatural strength, its influence had not yet departed.

"Simpson," I said, "whom have you got there?"

"I beg your pardon, sir, but I have just told Mr. Lethbridge that he could not see you. I did not think you looked well, sir."

"Show Mr. Lethbridge in. I am perfectly all right."

"I am afraid I should not have called," said Mr. Lethbridge, as he entered the room. "You do not look well."

"I am better than I have been for months," was my answer. "Sit down, won't you?"

He gave me a quick, searching glance, and then took the chair to which I had pointed. There were marks of suffering in his face. Although he was calm and collected and showed no signs of emotion whatever, I thought I saw in his eyes a strange, haunted look.

"I am afraid I did not receive you very cordially yesterday," he said presently. "You see it--it was the shock."

"Of course it was," was my answer. "I understand how you must be feeling."

"Do you?" he replied wearily. "I don't."

"Don't what?" I asked.

"Understand. I understand nothing. I am bewildered. I am in h.e.l.l."

He spoke very quietly although his voice was strained and somewhat hoa.r.s.e.

"You didn't sleep last night," I suggested.

"No," he replied, with a sigh, "I didn't sleep. I suppose I am regarded as a hard man, Mr. Erskine?"

To this I made no reply. I knew he was pa.s.sing through a terrible experience, and, strange as it may seem, I wanted to do nothing to lighten his burden.

"I don't know why I have come to you at all," he went on. "You are a comparative stranger to me--indeed, a few months ago I did not know of your existence--and yet something drew me here. I suppose it is because you were fond of him."

"I loved him almost like a brother," was my reply. "If I had been his father, I should be a proud man."

He looked at me steadily for a few minutes in silence.

"I have learnt one thing anyhow," he said at length.

"What is that?"

"That one cannot destroy the ties of blood. Yes! Yes! I know I had disinherited him; driven him from home; told him he was no longer a son of mine. Yes! told him that I had put him outside my life. But it was a lie! I had not! I could not! Oh, the tragedy of it!"