“But perhaps the police had some reasonable plan.  It was possible, but it was very unlikely.  The British policeman is a grand fellow, brave as a lion and ready to march cheerfully into the mouth of hell if duty calls.  But he knows no tactics.  His very courage is almost a disadvantage, leading him to disdain reasonable caution.  I felt that our guardians were again going to sacrifice themselves to these vermin.  It was terrible.  It was a wicked waste of precious lives.  Could nothing be done to prevent it?

“According to Mrs. Kosminsky, the ‘chentlemens’ were in the second floor front—­the room with the sliding panel.  Then I could, at least, keep a watch on them.  I walked slowly upstairs gnashing my teeth with irritation.  The sacrifice was so unnecessary.  I could think, offhand, of half a dozen ways of annihilating these wretches without risking a single hair of any decent person’s head.  And here were the police, with all the resources of science at their disposal and practically unlimited time in which to work, actually contemplating a fight with all the odds against them!

“I stole into the second floor front and, by the light of a match, found the cupboard.  The inside panel—­as I will call the one on my side—­slid back without a sound.  There was now only the second panel between me and the next room, and I could plainly hear the murmur of voices and sounds of movement.  But I could not distinguish what was being said; and as this was of some importance, I determined to try the other panel.  Grasping the handle, I gave a firm but gradual pull, and felt the panel slide back quite silently for a couple of inches.  Instantly the voices became perfectly distinct and a whiff of foul, stuffy air came through, with a faint glimmer of light; by which I knew that the cupboard on their side was at least partly open.

“‘I tell you, Piragoff,’ a voice said in Russian, ’you are nervous about nothing.  The police are looking for us, but they know none of us by sight.  We can go about quite safely.’

“‘I am not so sure,’ replied another voice—­presumably Piragoff’s.  ’The babbling fool who let us the house may talk more; and who knows but some of our own people may betray us.  That woman Kosminsky looked very queerly at us, I thought.’

“‘Bah!’ exclaimed the other.  ’Come and lie down, Piragoff.  Tomorrow we will leave this place and separate.  We shall go away for a time and they will forget us.  Put some more coke in the stove and let us go to sleep.’

“How incalculable are the groupings of factors that evolve the causation of events!  Those last words of the invisible ruffian seemed quite trivial and inconsequent; and yet they framed his death warrant.  I did not myself realize it fully at the moment.  As I closed the slide and stepped back, I was conscious only that a useful train of thought had been started.  ‘Put some more coke in the stove and let us go to sleep.’  Yes; there was a clear connection between the idea of ‘stove’ and that of ‘sleep,’ a sleep of infinite duration.  Therein lay the solution of the problem.