But she never finished the sentence. At that moment someone caught her wrist in a grip of steel, and wrenched the pistol from her.

"Come, come, Miss McLeod," said Fuller. "This is very un-neighbourly of you."

Myra looked round her in despair. There must be some way out of this.

She cudgelled her brains to devise some means of getting the better of her captives. Fuller laid the pistol on the table and sat down.

"You need not be alarmed," he said. "We shall not hurt you. You will be left here, that is all. And we shall get safely away. After this we shall not be able to leave your precious lover with you, but Hilderman insists that he shall not be hurt, and we shall take him to Germany and treat him as a prisoner of war."

Then Myra had an inspiration. She turned her head towards Fuller, as if she were looking about two feet to the right of his head.

"You may as well kill me as leave me here," she said calmly.

"Nonsense," said Hilderman. "If we leave you here, and see that you have no means of getting away by sea, you will have to find your way across the hills or round the cliffs. There is no road, and by the time you return to civilisation we shall be clear."

"That's very thoughtful of you," said Myra. "You bargain on my falling over a precipice or something. A blind girl would have a splendid chance of getting back safely!"

"Good heavens!" Hilderman cried. "I thought you must be able to see.

Fuller, this means that that fellow Burnham came with her, and is close at hand. What in the name----"

But he, too, was interrupted, for a great, gaunt figure flashed like some weird animal through the window. A long bare arm reached over Fuller's shoulder and s.n.a.t.c.hed the pistol.

"Yes, Mr. Burnham is with her," said Dennis quietly, as he stood in front of them, stripped to the waist, the water pouring off him in streams, and covered them with the revolver.

Hilderman and Fuller von Guernstein held up their hands as requested.

"This is very awkward," said Fuller. "We shall have to let that wretched Ewart go."

And then Dennis swayed, threw up his arms, and fell sideways, full length on the floor. Myra glanced at him, and threw herself on her knees beside the prostrate form.

"Dead!" she screamed. "_Dead!_"

Hilderman pushed her gently aside, and knelt down to examine Dennis.

"It's his heart," he announced. "Come Hugo. We're safe now, and the girl's blind. Let's get away."

CHAPTER XVIII.

THE TRUTH REVEALED.

I will here resume my own narrative.

When I came to myself I was dazed and aching, but, so far as I could discover, there were no bones broken. The curious part about it was the rapidity with which I recalled my fall into the cavern. When I found I could move my limbs freely I sat up, and discovered that I was in a small cabin on board a steamer. I stood up and stretched myself.

I was feeling weak and ill, but that would pa.s.s off I thought. A minute's speculation decided me that I was on board the _Fiona_, in which case I was shanghaied.

I knew that if I valued my life I must act at once. I opened the door of the cabin, and was surprised to find that it was unlocked. Then I crept cautiously in the shadows of the dawn up the companion-ladder to the deck. Though I heard voices I could see no one close to me. I stole along the deck and listened. The voices were talking quite freely in German. Where could we be? And, more important still, where were we going?

I looked around me, and saw that we were steaming slowly down a narrow loch, surrounded by mountains which stretched right down to the sh.o.r.es. I looked across the deck and almost shouted out in my surprise. For there, moving gracefully alongside of us, was a submarine. There were two officers on the deck of the submarine chatting with Hilderman and Fuller, who were leaning over the rail of the _Fiona_. A submarine! A German submarine in a peaceful Scottish loch! Then this was the secret base we had discussed. I looked up at the wheel-house. In front of it was the very searchlight, with its curious condenser that I had seen in the cavern.

What could it mean? I decided to slip overboard unseen, if possible, swim to the sh.o.r.e, and get back over the rocks to the mouth of the loch, and give the alarm if I should be fortunate enough to attract the attention of any pa.s.sing steamer.

But suddenly an idea struck me. I crept quickly up the ladder to the deckhouse, threw my arms round the man at the wheel, flung him down on to the deck, and swung the wheel round with all the strength I had in me. There was a dull, crunching sound as the yacht lurched round. A groaning shiver shook her, and, if I may be pardoned the ill.u.s.tration, it felt exactly as if the ship were going to be sick. There were hoa.r.s.e cries from the men, and as the _Fiona_ righted herself I looked astern. There was a frothy, many-coloured effervescence of oil and water.

The submarine had disappeared! The yacht was nearing the head of the loch. It was now or never. I made a dash for the side, but Fuller was before me. He tripped me up, and I fell heavily to the deck, bruising myself badly and giving my head a terrible b.u.mp. I put up my arm in a last feeble attempt to defend myself. Fuller's hands closed on my throat and nearly choked the life out of me, and as I sank back, struggling for breath, a loud cry rang out from Hilderman.

"Guernstein! Guernstein!" he yelled.

Fuller let me go and ran to Hilderman. I lifted myself on my elbow.

Somehow or other I would crawl to the side, and get away before he came back to finish me, but as I looked out over the stern I was rooted to the spot by the sight that met my eyes. Or was I deluding myself with the fantastic delirium of a dying man? Not four hundred yards away was a motor-boat. It was Hilderman's _Baltimore II._, and in it were Myra, my poor Myra, and Garnesk and Angus, all wearing motor-goggles. But, strangest of all, a British destroyer was puffing serenely behind them. No, I must be dreaming. Garnesk had told me he was sending gla.s.ses for Myra. He had mentioned his connection with the naval authorities. This must be the nightmare of death-agony.

Then Fuller rushed up the wheel-house ladder and jumped on to the searchlight platform. Suddenly there flashed out on the grey light of the dawn a vivid green ray. So, then, the mystery was solved--but, alas! too late. The green ray was produced by a searchlight, and every man on the destroyer would be blind. I looked back, and as I did so I remembered, with an uncanny distinctness, old General McLeod's words, "The rock came to me." The warship seemed suddenly to grow double its size, and then double that, and so on, growing bigger and bigger until it appeared to fill the entire loch, and spread out the whole length of the horizon. I could even see a gold signet-ring on the finger of a young officer on the bridge. I looked round at the details of the boat; it stood out in amazing clearness. If one man on that ship, hundreds of yards away, had opened his mouth I could have counted his teeth. Suddenly I gasped with astonishment as I awoke to the fact that every man on board the destroyer was wearing motor-goggles! I had no time to speculate about this new surprise, for then the _Fiona_, left to her own devices, suddenly crashed ash.o.r.e. The ship shook and shivered, and Fuller was thrown on his face beside the searchlight, and as I looked again the destroyer had resumed its normal proportions.

Then the crew of the _Fiona_ rushed about the deck in mad terror, until, evidently at the wise suggestion of one of their number, they decided to wait calmly and give themselves up. Hilderman, closely followed by Fuller, sprang ash.o.r.e, and made for the mountains. Half a dozen shots rang out from the destroyer, and a rifle bullet checked Fuller's progress before he had gone more than a few yards.

Hilderman, however, managed to reach the shelter of a ridge of rock, and I watched him as he scuttled up the mountain side, and made straight for a long grey rock which protruded from the foot of a steep crag. And as I looked, and saw him go to the rock and open a door in it, I realised that it was really a great, grey, lean-to shed, cunningly concealed. Hilderman had scarcely opened the door when a huge, dark shadow seemed to fall out of the shed and envelop him. It was Sholto. Blind, and half-mad with fury, he sprang at Hilderman's throat with the unerring aim of his breed. The wretched man staggered and fell, and Sholto----.

I turned away from the sickening sight, and looked over the side, and saw Myra standing up, waving to me, as they drew alongside the wrecked _Fiona_.

And then I'm afraid I must have fainted.

I lay on the sofa in Myra's den, and Myra--G.o.d bless her!--was kneeling beside me. Sholto was with us too, looking incredibly wise in a pair of motor-goggles.

"So you see, darling," said Myra, "the gla.s.ses cured me completely, and I can see just as well as ever." And I shall not repeat what I said in reply to such glorious news.

"Tell me, dear," I asked shortly, "what exactly happened with Dennis?

I haven't quite got that."

"Well, he saw me on my way to Glasnabinnie," she explained, "and was determined to follow. He couldn't find a boat of any kind, so he swam!

Angus saw him in the water and ran and told daddy. When they found there was no boat they went and fetched the one on the loch, carried it down to the sea, and called Hamish. Then they pulled across. Then, you see, when Dennis had his heart attack, I thought he was only pretending. I thought he saw that we should never be able to get away again, and that if he pretended to be dead they would leave us alone.

So I followed his lead. I was terribly frightened when I couldn't make him answer me after they had gone, but before I could do anything daddy and the men arrived. Angus stopped with me, and told me where the _Fiona_ had gone. We took the _Baltimore_ because she is much faster than our boat. He must have been a duffer to lose that race we had. And then daddy and Hamish took Dennis--I refuse to call him Mr.

Burnham after this--and brought him here and sent for Dr. Whitehouse."

"I'm thankful he's out of danger," I said fervently.

"But the doctor says he must take it very, very gently for a long time, and he won't be able to walk much for months. Did he know he had this heart trouble?"

I had scarcely finished explaining the extent of Dennis's heroism when Garnesk arrived.

"Hilderman's dead!" he said. "He made a full confession. It seems he is a German, and his name's von Hilder. He has lived most of his life in America. He is a brilliant physicist, and has done some big things with electricity and light. He was here to prepare the submarine base you found, and he also got on with a new invention--The Green Ray. Of course he didn't give the secret of that away, but we have the searchlight, and I have already tumbled to it partly. It is practically a new form of light.

"It is formed by pa.s.sing violet and orange rays through tourmaline and quartz respectively. The accident to Miss McLeod was their first intimation of its blinding properties, and to the end he knew nothing about the suffocation part of it. I find by experiment that when the two rays are switched on simultaneously the air does not become de-oxygenised, but when you put the violet ray first it does, and it remains so until the orange ray is applied. The effect that Hilderman imagined, and succeeded in producing, was a ray of light which should so alter the relative density of the air as to act as a telescope.

He's done it, and it's one of the finest achievements of science.

However, I have a piece of wonderful news for you."