“Dicky also said,” Ralph remarked, “that the man was intrusted with some business over here for his government.  Nasty underhand lot, those republics of the Southern Hemisphere.  I dare say he is driven to be a bit mysterious to carry the thing through.”

“I shall know more about it soon, I hope,” I answered.  “I’ll go and ring Freddy up, if you don’t mind, now.”

Ralph nodded.

“I’m off to my room, at any rate, old chap,” he said.  “Groves is going abroad for a month’s holiday, and he has brought some papers for me to look through.  See you some time to-morrow.”

I made my way into the little sitting-room which belonged to the suite of rooms my brother had placed at my disposal.  There I rang up Lord Frederic Maynard, my first cousin, and a junior member of the government.  The butler told me that Lord Frederic was dining, but would doubtless speak to me for a moment.  In a minute or two I heard his familiar voice.

“Freddy,” I said, “I want to meet the Chinese ambassador.”

“Eleven till one to-night here,” he answered.  “What the devil do you want with him?”

“Do you mean that he is coming to your house to-night?” I asked.

“Exactly,” Freddy answered.  “We’ve a political reception, semi-diplomatic.  I saw our old friend only yesterday, and he reminded me that he was coming.”

“You’re a brick, Freddy!” I answered.  “I’ll be round.”

“You have not answered my question,” he reminded me.

“I’ll tell you later,” I answered, and rang off.

I was at Maynard House very soon after eleven, and, after chatting for a little while with my hostess, I hung around near the entrance, watching the arrivals.  About midnight His Excellency the Chinese ambassador was announced, and I felt a little thrill of exultation.  I was right!  The tall, powerful-looking man whom I saw bowing over my cousin’s hand was indeed the person whom I had seen with Delora a few hours ago.  I ran Freddy to ground, and presently I found myself also bowing before His Excellency.  He regarded me through his horn-rimmed spectacles with a benign and pleasant expression.  I had been in the East, and I talked for a few moments upon the subjects which I thought would interest him.

“Your Excellency, I dare say, is well acquainted with London,” I remarked, apropos of something he said.

“I know your great city only indifferently,” he answered.  “I am always anxious to take the opportunity of seeing more of it.”

“Last evening, for instance,” I remarked, “Your Excellency was, I think, exploring a very interesting neighborhood.”

“Last evening,” he repeated.  “Let me think.  No, not last evening, Captain Rotherby!  I was giving a little dinner at my own house.”

I looked at him for a moment in silence.  There was nothing to be learned from his expression.

“I thought,” I said, “that I saw your Excellency in a street near Shaftesbury Avenue, leaving a small foreign restaurant,—­the Cafe Universel.  Your Excellency was with a man named Delora.”