I nodded my head.  I had no idea how he had got his information, for as far as I was aware George was the only person who had any knowledge of my secret.

“And I believe you were just on the point of success when you were arrested?”

“Theoretically I was,” I said.  “These matters don’t always work out quite so well when you put them to a practical test.”

“Still, you yourself were quite satisfied with the prospects?”

I nodded again.

“And unless I am wrong, this new explosive will be immensely more powerful than anything now in use?”

“Immensely,” I repeated; “in fact, there would be no practical comparison between them.”

“Can you give me any idea as to its strength?”

I hesitated.  “According to my calculations,” I said slowly, “it ought to prove at least twenty times as powerful as gun-cotton.”

Savaroff uttered a hoarse exclamation and sat upright in his seat.

“Are you speaking the truth?” he asked roughly.

I stared him full in the face, and then without answering turned back to McMurtrie.

The latter made a gesture with his hand.  “Leave the matter to me, Savaroff,” he said sharply.  “I understand Mr. Lyndon better than you do.”  Then addressing me:  “Supposing you had all the things that you required, how long would it take you to manufacture some of this powder—­or whatever it is?”

“It’s difficult to say,” I answered.  “Perhaps a week; perhaps a couple of months.  I could make the actual stuff at once provided I had the materials, but it’s a question of doing it in such a way that one can handle it safely for practical purposes.  I was experimenting on that very point at the time of my arrest.”

McMurtrie nodded his head slowly.  “You have been candid with us,” he said, “and now I will be equally candid with you.  My friend M. Savaroff and myself are very largely interested in the manufacture of high explosives.  The appearance of an invention like yours on the market would be a very serious matter indeed for us.  On the other hand, if we had control of it, we should, I imagine, be in a position to dictate our own terms.”

“You certainly would,” I said; “there is no question about that.  My explosive would be no more expensive to manufacture than cordite.”

“So you see when some exceedingly convenient chance brought you in through our kitchen window it naturally occurred to me to invite you to stay and discuss the matter.  You happen to be in a position in which you could be useful to us, and I think that we, on the other hand, might be of some assistance to you.”

He leant back and watched me with that cold smile of his.

“What do you say, Mr. Lyndon?” he added.

I did some rapid but necessary thinking.  It was quite true that the new explosive would knock the bottom out of the present methods of manufacture, and McMurtrie’s interests in the matter might well be large enough to make him run the risk of helping me.  There seemed no reason to doubt that he was speaking the truth—­and yet, somehow or other I mistrusted him—­mistrusted him from my soul.