The light burnt steadily in Madame de Mauban's window.

Then I heard the faintest, faintest sound: it came from behind the door which led to the drawbridge on the other side of the moat.

It but just reached my ear, yet I could not be mistaken as to what it was.
It was made by a key being turned very carefully and slowly.

Who was turning it?
And of what room was it the key?
There leapt before my eyes the picture of young Rupert, with the key in one hand, his sword in the other, and an evil smile on his face.

But I did not know what door it was, nor on which of his favourite pursuits young Rupert was spending the hours of that night.
I was soon to be enlightened, for the next moment--before my friends could be near the chateau door--before Johann the keeper would have thought to nerve himself for his task--there was a sudden crash from the room with the lighted window.