“How?”

“We’ll go into that presently.  Let us hear about your adventures first.”

I gave him a full account of my movements from the time when we parted to that of my arrival home, omitting no incident that I was able to remember and, as far as I could, reconstituting my exceedingly devious homeward route.

“Your retreat was masterly,” he remarked with a broad smile.  “I should think that it would have utterly defeated any pursuer; and the only pity is that it was probably wasted on the desert air.  Your pursuer had by that time become a fugitive.  But you were wise to take these precautions, for, of course, Weiss might have followed you.”

“But I thought he was in Hamburg?”

“Did you?  You are a very confiding young gentleman, for a budding medical jurist.  Of course we don’t know that he is not; but the fact that he has given Hamburg as his present whereabouts establishes a strong presumption that he is somewhere else.  I only hope that he has not located you, and, from what you tell me of your later methods, I fancy that you would have shaken him off even if he had started to follow you from the tea-shop.”

“I hope so too.  But how did that woman manage to stick to me in that way?  What was the mistake we made?”

Thorndyke laughed grimly.  “It was a perfectly asinine mistake, Jervis.  You started up Kennington Park Road on a leisurely, jog-trotting omnibus, and neither you nor I remembered what there is underneath Kennington Park Road.”

“Underneath!” I exclaimed, completely puzzled for the moment.  Then, suddenly realizing what he meant, “Of course!” I exclaimed.  “Idiot that I am!  You mean the electric railway?”

“Yes.  That explains everything.  Mrs. Schallibaum must have watched us from some shop and quietly followed us up the lane.  There were a good many women about and several were walking in our direction.  There was nothing to distinguish her from the others unless you had recognized her, which you would hardly have been able to do if she had worn a veil and kept at a fair distance.  At least I think not.”

“No,” I agreed, “I certainly should not.  I had only seen her in a half-dark room.  In outdoor clothes and with a veil, I should never have been able to identify her without very close inspection.  Besides there was the disguise or make-up.”

“Not at that time.  She would hardly come disguised to her own house, for it might have led to her being challenged and asked who she was.  I think we may take it that there was no actual disguise, although she would probably wear a shady hat and a veil; which would have prevented either of us from picking her out from the other women in the street.”

“And what do you think happened next?”