"I could not speak to her," continued Sophia, "I felt stifled, stupefied by what I had heard! I could bear no more; and so I rose and left her, and walked down some stairs, and somehow found myself back in our own room again! I was more bewildered than ever. I looked for the cheque, but there was nothing, and soon I was forced to believe that the whole thing was imaginary. Still, I was not wholly satisfied. You may remember how I questioned you one evening when you were reading the _Doll's House_ to me; well, your answers quite reassured me for the time. I told myself that my suspicions were too wildly improbable not to have been a delusion. I was even afraid that my brain must be slightly affected, for I had always prided myself upon having my imagination under thorough control. But by degrees, Peter--by degrees--I began to doubt again whether it was really nothing but fancy on my part. I noticed that your manner was suspiciously odd at times. I discovered that there was one drawer in your secretary that you kept carefully locked. I caught your eye wandering towards the clock from time to time. _What_ I suspected I hardly know; but I felt certain that I should find the explanation of that mystery in the locked drawer. I tried key after key, until I found one that fitted. Oh, I am not at all ashamed of it! Had I not a _right_ to know? There were no letters, nothing but a cheque-book; but that cheque-book proved to me that, after all, I had imagined nothing: all the cheques were the same as the one I found on the carpet! I tore one out and kept it by me, and from that time I watched you closely. I saw how restless and impatient you were this evening, and I was certain that you were intending to use a cheque from that book. You were bent on getting back to the _Boomerang_, and I was equally determined that, if I could help it, you should not go alone. Only I could not be quite sure how you managed to get there, and at last I hit upon a little device for finding out. There is no such person as Professor Dibbs, Peter; I invented him to put you off your guard. As I passed into the other room with the lamp, I saw you, reflected in the mirror over the study chimneypiece, rise and go to the drawing-room mantelpiece: you had a slip of paper in your hand--a cheque, of course. I had the cheque I tore out hidden in the waistband of my dress; and so, as soon as I saw you slip your cheque behind the clock in the drawing-room, I put _my_ cheque behind the one in the study. I was on the deck at once, and it was dark, but I could hear your voice and another's--round a corner. I held my breath and listened. What I heard, you know!"