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 Japs 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.