It was my first visit to the scene of the crime—­a high, dingy, narrow-chested house, prim, formal, and solid, like the century which gave it birth.  Lestrade’s bulldog features gazed out at us from the front window, and he greeted us warmly when a big constable had opened the door and let us in.  The room into which we were shown was that in which the crime had been committed, but no trace of it now remained save an ugly, irregular stain upon the carpet.  This carpet was a small square drugget in the centre of the room, surrounded by a broad expanse of beautiful, old-fashioned wood-flooring in square blocks, highly polished.  Over the fireplace was a magnificent trophy of weapons, one of which had been used on that tragic night.  In the window was a sumptuous writing-desk, and every detail of the apartment, the pictures, the rugs, and the hangings, all pointed to a taste which was luxurious to the verge of effeminacy.

“Seen the Paris news?” asked Lestrade.

Holmes nodded.

“Our French friends seem to have touched the spot this time.  No doubt it’s just as they say.  She knocked at the door—­surprise visit, I guess, for he kept his life in water-tight compartments—­he let her in, couldn’t keep her in the street.  She told him how she had traced him, reproached him.  One thing led to another, and then with that dagger so handy the end soon came.  It wasn’t all done in an instant, though, for these chairs were all swept over yonder, and he had one in his hand as if he had tried to hold her off with it.  We’ve got it all clear as if we had seen it.”

Holmes raised his eyebrows.

“And yet you have sent for me?”

“Ah, yes, that’s another matter—­a mere trifle, but the sort of thing you take an interest in—­queer, you know, and what you might call freakish.  It has nothing to do with the main fact—­can’t have, on the face of it.”

“What is it, then?”

“Well, you know, after a crime of this sort we are very careful to keep things in their position.  Nothing has been moved.  Officer in charge here day and night.  This morning, as the man was buried and the investigation over—­so far as this room is concerned—­we thought we could tidy up a bit.  This carpet.  You see, it is not fastened down, only just laid there.  We had occasion to raise it.  We found——­”

“Yes?  You found——­”

Holmes’s face grew tense with anxiety.

“Well, I’m sure you would never guess in a hundred years what we did find.  You see that stain on the carpet?  Well, a great deal must have soaked through, must it not?”

“Undoubtedly it must.”

“Well, you will be surprised to hear that there is no stain on the white woodwork to correspond.”

“No stain!  But there must——­”

“Yes, so you would say.  But the fact remains that there isn’t.”

He took the corner of the carpet in his hand and, turning it over, he showed that it was indeed as he said.