"Well, there is a chance of it, anyhow," amended Poirot. "Also, I learn that a swarthy man, a foreigner of some kind, was inquiring about the occupants of No. 4 only this morning. Therefore, mon ami, I fear that you must forswear your beauty sleep tonight, and join me in my all-night vigil in the flat below—armed with that excellent revolver of yours, bien entendu!"
"Rather," I cried with enthusiasm. "When shall we start?"
"The hour of midnight is both solemn and suitable, I fancy. Nothing is likely to occur before then."
At twelve o'clock precisely, we crept cautiously into the coal-lift and lowered ourselves to the second floor. Under Poirot's manipulation, the wooden door quickly swung inwards, and we climbed into the flat. From the scullery we passed into the kitchen where we established ourselves comfortably in two chairs with the door into the hall ajar.
"Now we have but to wait," said Poirot contentedly, closing his eyes.
To me, the waiting appeared endless. I was terrified of going to sleep. Just when it seemed to me that I had been there about eight hours
