’Surely there are details in her story which, if we looked at in cold blood, would excite our suspicion.  These burglars made a considerable haul at Sydenham a fortnight ago.  Some account of them and of their appearance was in the papers, and would naturally occur to anyone who wished to invent a story in which imaginary robbers should play a part.  As a matter of fact, burglars who have done a good stroke of business are, as a rule, only too glad to enjoy the proceeds in peace and quiet without embarking on another perilous undertaking.  Again, it is unusual for burglars to operate at so early an hour, it is unusual for burglars to strike a lady to prevent her screaming, since one would imagine that was the sure way to make her scream, it is unusual for them to commit murder when their numbers are sufficient to overpower one man, it is unusual for them to be content with a limited plunder when there was much more within their reach, and finally, I should say, that it was very unusual for such men to leave a bottle half empty.  How do all these unusuals strike you, Watson?’

’Their cumulative effect is certainly considerable, and yet each of them is quite possible in itself.  The most unusual thing of all, as it seems to me, is that the lady should be tied to the chair.’

’Well, I am not so clear about that, Watson, for it is evident that they must either kill her or else secure her in such a way that she could not give immediate notice of their escape.  But at any rate I have shown, have I not, that there is a certain element of improbability about the lady’s story?  And now, on the top of this, comes the incident of the wineglasses.’

‘What about the wineglasses?’

‘Can you see them in your mind’s eye?’

‘I see them clearly.’

’We are told that three men drank from them.  Does that strike you as likely?’

‘Why not?  There was wine in each glass.’

’Exactly, but there was beeswing only in one glass.  You must have noticed that fact.  What does that suggest to your mind?’

‘The last glass filled would be most likely to contain beeswing.’

’Not at all.  The bottle was full of it, and it is inconceivable that the first two glasses were clear and the third heavily charged with it.  There are two possible explanations, and only two.  One is that after the second glass was filled the bottle was violently agitated, and so the third glass received the beeswing.  That does not appear probable.  No, no, I am sure that I am right.’

‘What, then, do you suppose?’

’That only two glasses were used, and that the dregs of both were poured into a third glass, so as to give the false impression that three people had been here.  In that way all the beeswing would be in the last glass, would it not?  Yes, I am convinced that this is so.  But if I have hit upon the true explanation of this one small phenomenon, then in an instant the case rises from the commonplace to the exceedingly remarkable, for it can only mean that Lady Brackenstall and her maid have deliberately lied to us, that not one word of their story is to be believed, that they have some very strong reason for covering the real criminal, and that we must construct our case for ourselves without any help from them.  That is the mission which now lies before us, and here, Watson, is the Sydenham train.’