This question of the unfastened window easily narrowed the field of search for the murderer.

He must belong to the house, unless he had an accomplice, which I do not believe he had; unless--unless Mademoiselle Stangerson herself had seen that that window was not fastened from the inside.

But, then,--what could be the frightful secret which put her under the necessity of doing away with obstacles that separated her from the murderer?
"I seized hold of the ladder, and we returned to the back of the chateau to see if the window of the chamber was still half-open.

The blind was drawn but did not join and allowed a bright stream of light to escape and fall upon the path at our feet.

I planted the ladder under the window.