Again Sonia shrugged her shoulders. "I can't say. The doctor and my father never tell me anything that they can keep to themselves. Most of what I know I have picked up from listening to them and putting things together in my own head afterwards. I am useful to them, and to a certain point they trust me; but only so far. They know I hate them both."

She made the statement with a detached bitterness that spoke volumes for its sincerity.

I felt too that she was telling me the truth about George. A man who could lie as he did at the trial was quite capable of betraying his country or anything else. Still, the infernal impudence and treachery of his selling my beautiful torpedo to the Germans filled me with a furious anger such as I had not felt since I crouched, dripping and hunted, in the Walkham woods.

I looked up at Sonia, who was leaning forward and watching me with those curious half-sullen, half-pa.s.sionate eyes of hers.

"Why did George tell those lies about me at the trial?" I asked.

"I don't know for certain; I think he wanted to get rid of you, so that he could steal your invention. Of course he saw how valuable it was. You had told him about the notes, and I think he felt that if you were safely out of the way he would be able to make use of them himself."

"He must have been painfully disappointed," I said. "They were all jotted down in a private cypher. No one else could possibly have understood them."

She nodded. "I know. He offered to sell them to us. He suggested that the Germans might be willing to pay a good sum down for them on the chance of being able to make them out."

Angry as I was, I couldn't help laughing. It was so exactly like George to try and make the best of a bad speculation.

"I can hardly see the doctor doing business on those lines," I said.

"It was too late in any case," she answered calmly. "Just after he made the offer you escaped from prison." There was another pause. "And what were you all doing down in that G.o.d-forsaken part of the world?"

I demanded.

The question was a little superfluous as far as I was concerned, but I felt that Sonia would be expecting it.

"Oh, we weren't there for pleasure," she said curtly. "We wanted to be near Devonport, and at the same time we wanted a place that was quite quiet and out-of-the-way. Hoffman found the house for us, and we took it furnished for six months."

"It was an extraordinary stroke of luck," I said, "that I should have come blundering in as I did."

Sonia laughed venomously. "It was the sort of thing that would happen to the doctor. The Devil looks after his friends."

"As a matter of fact," I objected, "I was thinking more of myself."

Sonia took no notice of my interruption. "Why, it meant everything to him," she went on eagerly. "It practically gave him the power to dictate his own terms to the Germans. You see, he knew something about their plans. He knew--at least he could guess--that the moment war was declared they meant to make a surprise attack on all the big dockyards--just like the j.a.ps did at Port Arthur. Well, think of the difference an explosive as powerful as yours would make! Why, it would put England absolutely at their mercy. They could blow up Portsmouth, Sheerness, and Devonport before any one really knew that the war had started."

She spoke rapidly, almost feverishly, leaning forward and gripping the edge of the table, till the skin showed white on her knuckles. I think I was equally excited, but I tried not to show it.

"Yes," I said; "it sounds a promising notion."

"Promising!" she echoed. "Well, it was promising enough for the Germans to offer us anything we wanted the moment we could give them the secret. Now perhaps you can understand why we were so hospitable and obliging to you."

"And you believe McMurtrie never meant to keep his word to me?" I asked.

She laughed again scornfully. "If you knew him as well as I do, you wouldn't need to ask that. He would simply have disappeared with the money and left you to rot or starve."

I took out my case, and having given Sonia a cigarette, lit one myself.

"It's an unpleasant choice," I said, "but I gather there's a possible alternative."

She lighted her own cigarette and threw away the match. Her dark eyes were alight with excitement.

"Listen," she said. "All the Germans want is the secret. Do you suppose they care in the least whom they get it from? You have only got to prove to them that you can do what you say, and they will pay you the money just as readily as they would the doctor."

There was a magnificent simplicity about the idea that for a moment almost took my breath away.

"How could I get in touch with them?" I asked.

She leaned forward again, and lowered her voice almost to a whisper.

"I can take you now--now right away--to the two men who are in charge of the whole business. I know that they have an absolutely free hand to make the best terms they can."

"Who are they?" I demanded, with an eagerness I made no attempt to hide.

"Their names are Seeker and von Brunig, and they're living in a small bungalow on Sheppey. They are supposed to be artists. As a matter of fact, von Brunig is a captain in the Germany Navy. I don't know who the other man is; I think he has been sent over specially about the powder."

Her statement fitted in so exactly with what I had already found out from Latimer and Gow, that I hadn't the remotest doubt she was telling me the literal truth. Of its importance--its vital importance to England--there could be no question. I felt my heart beating quickly with excitement, but the obvious necessity for fixing on some scheme of immediate action kept my brain cool and clear. The first thing was to gain a moment or two to think in.

"You realize what all this means, Sonia?" I said. "You're quite prepared to throw over your father and McMurtrie? You know how the doctor deals with people who betray him--when he gets the chance?"

"I am not afraid of them," she answered defiantly. "They are nothing to me; I hate them both--and Hoffman too. It's you I want. You are the only man I ever have wanted." She paused, and I saw her breast rising and falling rapidly with the stress of her emotion. "We will go away together--somewhere the other side of the world--America, Buenos Ayres--oh, what does it matter where?--there are plenty of places!

What does anything matter so long as we love each other!"

She half rose to her feet, but I jumped up first.

"One moment, Sonia," I said. "Let me think."

Thrusting my hands in my pockets, I strode across the room, and pulling up in front of the little window, stared out across the marsh.

As I did so, I felt as if some one had suddenly placed a large handful of crushed ice inside my waistcoat. About two hundred yards away, strolling cheerfully and unconcernedly towards the hut, was the charming but painfully inopportune figure of Joyce.

It was a most unpleasant second. In my excitement at listening to Sonia's revelations, I had clean forgotten for the time that Joyce was coming, and now it was too late for the recollection to be of much practical use. Except for an earthquake, or the sudden arrival of the end of the world, nothing could stop her from reaching the hut in another five minutes.

I stood quite still, racking my brains as to what was the best thing to do. It was no use trying to signal to her from the window, for Sonia would be certain to see me; while if I made some excuse for going outside, Joyce would probably call out to me before I had time to warn her. My only hope seemed to lie in the chance of her hearing us talking as she came up to the door, in which case she would know at once that there was some one there and go straight on to the _Betty_.

I had just reached this conclusion when a queer sound behind me made me spin round as if I had been struck. Sonia, who had risen to her feet, was standing and facing me; her whole att.i.tude suggestive of a highly-annoyed tigress. I don't think I have ever seen such a malevolent expression on any human being's face in my life. For an instance we stood staring at each other without speaking, and then quite suddenly I realized what was the matter.

Clutched tight in her right hand was a letter--a letter which I recognized immediately as the one I had received from Joyce that morning. Like a fool I must have left it lying on the desk, and while I was looking out of the window she had evidently picked it up and read it.

I hadn't much time, however, for self-reproaches.

"So, you have been lying to me all through," she broke out bitterly.

"This girl is your mistress; and all the time you have simply been using me to help yourself. Oh, I see it all now. I see why you were so anxious to come to London. While I have been working and scheming for you, you and she ..." Her voice failed from very fury, and tearing the letter in pieces, she flung them on the ground at my feet.

I suppose I attempted some sort of reply, for she broke out again more savagely than ever.

"She _is_ your mistress! Do you dare to deny it, with that letter staring me in the face? Coming down to 'kiss you and be kissed by you,' is she? Well, she's used to that, at all events!" Her voice choked again, and with her hands clenched she made a quick step forward in my direction.

Then quite suddenly I saw her whole expression change. The anger in her eyes gave place to a gleam of recognition, and the next moment her lips parted in a peculiarly malicious smile. She was looking past me through the open window.

"Ah!" she said. "So that's why you were standing there! You didn't expect me to be here when she arrived, did you?" With a mocking laugh she turned to the doorway. "Never mind," she added viciously: "you will be able to introduce us."