I had, and, without making any noise,
opened the door.

"The gallery into which I went was well lit by a lamp with a reflector.
I felt a keen current of air and, on turning, found the window open, at
the extreme end of the gallery, which I call the 'off-turning' gallery,
to distinguish it from the 'right' gallery, on to which the apartment of
Mademoiselle Stangerson opened. These two galleries cross each other at
right angles. Who had left that window open? Or, who had come to open
it? I went to the window and leaned out. Five feet below me there was
a sort of terrace over the semi-circular projection of a room on the
ground-floor. One could, if one wanted, jump from the window on to
the terrace, and allow oneself to drop from it into the court of the
chateau. Whoever had entered by this road had, evidently, not had a
key to the vestibule door. But why should I be thinking of my previous
night's attempt with the ladder?--Because of the open window--left open,
perhaps, by the negligence of a servant? I reclosed it, smiling at
the ease with which I built a drama on the mere suggestion of an open
window.

"Again the cry of the Bete du Bon Dieu!--and then silence. The rain
ceased to beat on the window. All in the chateau slept. I walked with
infinite precaution on the carpet of the gallery. On reaching the corner
of the 'right' gallery, I peered round it cautiously. There was another
lamp there with a reflector which quite lit up the several objects in
it,--three chairs and some pictures hanging on the wall. What was I
doing there? Perfect silence reigned throughout. Everything was sunk
in repose. What was the instinct that urged me towards Mademoiselle
Stangerson's chamber? Why did a voice within me cry: 'Go on, to the
chamber of Mademoiselle Stangerson!' I cast my eyes down upon the
carpet on which I was treading and saw that my steps were being directed
towards Mademoiselle Stangerson's chamber by the marks of steps that
had already been made there. Yes, on the carpet were traces of footsteps
stained with mud leading to the chamber of Mademoiselle Stangerson.
Horror! Horror!--I recognised in those footprints the impression of
the neat boots of the murderer! He had come, then, from without in this
wretched night. If you could descend from the gallery by way of the
window, by means of the terrace, then you could get into the chateau by
the same means.

"The murderer was still in the chateau, for here were marks as of