I rushed into my room to change my coat, with the idea of hurrying round to Mrs. Marden’s to learn from her what the cause of my misfortune might be.  So shaken was I that I could hardly lace my boots.  Never shall I forget those horrible ten minutes.  I had just pulled on my overcoat when the clock upon the mantel-piece struck ten.

Ten!  I associated the idea with Miss Penclosa’s note.  It was lying before me on the table, and I tore it open.  It was scribbled in pencil in a peculiarly angular handwriting.

“My dear professor Gilroy [it said]:  Pray excuse the personal nature of the test which I am giving you.  Professor Wilson happened to mention the relations between you and my subject of this evening, and it struck me that nothing could be more convincing to you than if I were to suggest to Miss Marden that she should call upon you at half-past nine to-morrow morning and suspend your engagement for half an hour or so.  Science is so exacting that it is difficult to give a satisfying test, but I am convinced that this at least will be an action which she would be most unlikely to do of her own free will.  Forget any thing that she may have said, as she has really nothing whatever to do with it, and will certainly not recollect any thing about it.  I write this note to shorten your anxiety, and to beg you to forgive me for the momentary unhappiness which my suggestion must have caused you. 
                “Yours faithfully;
                                “Helen Penclosa.

Really, when I had read the note, I was too relieved to be angry.  It was a liberty.  Certainly it was a very great liberty indeed on the part of a lady whom I had only met once.  But, after all, I had challenged her by my scepticism.  It may have been, as she said, a little difficult to devise a test which would satisfy me.

And she had done that.  There could be no question at all upon the point.  For me hypnotic suggestion was finally established.  It took its place from now onward as one of the facts of life.  That Agatha, who of all women of my acquaintance has the best balanced mind, had been reduced to a condition of automatism appeared to be certain.  A person at a distance had worked her as an engineer on the shore might guide a Brennan torpedo.  A second soul had stepped in, as it were, had pushed her own aside, and had seized her nervous mechanism, saying:  “I will work this for half an hour.”  And Agatha must have been unconscious as she came and as she returned.  Could she make her way in safety through the streets in such a state?  I put on my hat and hurried round to see if all was well with her.

Yes.  She was at home.  I was shown into the drawing-room and found her sitting with a book upon her lap.

“You are an early visitor, Austin,” said she, smiling.

“And you have been an even earlier one,” I answered.