Imagine my surprise to see Kazanovitch already there, seated in the wrecked office, furiously smoking cigarettes and showing evident signs of having something very disturbing on his mind.  The moment he caught sight of me, he hurried forward.

“Is Professor Kennedy coming soon?” he inquired eagerly.  “I was going up to his laboratory, but I called up Nevsky, and she said he would be here at noon.”  Then he put his hand up to my ear and whispered, “I have found out who it was who shadowed Kharkoff.”

“Who?” I asked, saying nothing of my long search of the morning.

“His name is Revalenko—­Feodor Revalenko.  I saw him standing across the street in front of the house last night after you had gone.  When Kharkoff left, he followed him.  I hurried out quietly and followed both of them.  Then the explosion came.  This man slipped down a narrow street as soon as he saw Kharkoff fall.  As people were running to Kharkoff’s assistance, I did the same.  He saw me following him and ran, and I ran, too, and overtook him.  Mr. Jameson, when I looked into his face I could not believe it.  Revalenko—­he is one of the most ardent members of our organisation.  He would not tell me why he had followed Kharkoff.  I could make him confess nothing.  But I am sure he is an agent provocateur of the Russian government, that he is secretly giving away the plans that we are making, everything.  We have a plot on now—­perhaps he has informed them of that.  Of course he denied setting the bomb or trying to poison any of us, but he was very frightened.  I shall denounce him at the first opportunity.”

I said nothing.  Kazanovitch regarded me keenly to see what impression the story made on me, but I did not let my looks betray anything, except proper surprise, and he seemed satisfied.

It might be true, after all, I reasoned, the more I thought of it.  I had heard that the Russian consul-general had a very extensive spy system in the city.  In fact, even that morning I had had pointed out to me some spies at work in the public libraries, watching what young Russians were reading.  I did not doubt that there were spies in the very inner circle of the revolutionists themselves.

At last Kennedy appeared.  While Kazanovitch poured forth his story, with here and there, I fancied, an elaboration of a particularly dramatic point, Kennedy quickly examined the walls and floor of the wrecked office with his magnifying-glass.  When he had concluded his search, he turned to Kazanovitch.

“Would it be possible,” he asked, “to let this Revalenko believe that he could trust you, that it would be safe for him to visit you to-night at Saratovsky’s?  Surely you can find some way of reassuring him.”

“Yes, I think that can be arranged,” said Kazanovitch.  “I will go to him, will make him think I have misunderstood him, that I have not lost faith in him, provided he can explain all.  He will come.  Trust me.”