There was a short silence.

“How long have you been here?” I asked.  “What brought you to England?”

“We have been here just over three years,” she answered slowly.  “There was a man in London that Dr. McMurtrie and my father wanted to find.  Eight years ago he betrayed them in St. Petersburg.”

A sudden idea—­so wild as to be almost incredible—­flashed into my mind.

I moistened my lips.  “Who was he?” I asked steadily.

She shook her head.  “I don’t know his name.  I only know that he is dead.  I think Dr. McMurtrie would kill any one who betrayed him—­if he could.”

I crossed the room and sat down on the edge of the bed.  I felt strangely excited.

“And after that,” I said quietly, “I suppose the doctor thought he might as well stop here and do a little business?”

“I think it was suggested to him from Berlin.  He had sent them all sorts of information when we were in Paris, and, of course, as things are now, they were still more anxious to get hold of anything about the English army or navy.”  She paused.  “What they specially wanted were the plans of the Lyndon-Marwood torpedo.”

“Yes,” I said.  “I dare say they did.  A lot of people have wanted them, but unfortunately they’re not for sale.”

Sonia laughed softly.  “The exact price we paid for them,” she said, “was twelve thousand pounds.”

I sat up with a jerk.  This time my surprise was utterly genuine.

“You bought them!” I said incredulously.  “Bought them from some one in the Admiralty?”

Again Sonia shook her head.  “Don’t you remember what you read in the Daily Mail about the robbery at your offices in Victoria Street?”

I stared at her for a second, and then suddenly the real truth dawned on me.

“So George sold them to you?” I said.

She nodded.  “Ever since you went to prison the business has been going to pieces.  He wanted money badly—­very badly indeed.  Dr. McMurtrie found this out.  He found out too that there was a copy of the plans in the office, and—­well, you can guess the rest.  The burglary, of course, was arranged between them.  It was meant to cover your cousin in case the Government found out that the Germans had got hold of the plans.”

“And have they found out?” I asked.

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.