“Yes, yes, I know, but I am showing you the absurdity of your theory.  It can’t be correct, and we can’t believe in Marie Fauville’s innocence unless we are prepared to suppose an unheard-of thing, that M. Fauville took part in his own murder.  Why, it’s laughable!”

And he gave a laugh; but it was a forced laugh and did not ring true.

“For, after all,” he added, “you can’t deny that that is where we stand.”

“I don’t deny it.”

“Well?”

“Well, M. Fauville, as you say, took part in his own murder.”

This was said in the quietest possible fashion, but with an air of such certainty that no one dreamed of protesting.  After the work of deduction and supposition which Don Luis had compelled his hearers to undertake, they found themselves in a corner which it was impossible for them to leave without stumbling against unanswerable objections.

There was no longer any doubt about M. Fauville’s share in his own death.  But of what did that share consist?  What part had he played in the tragedy of hatred and murder?  Had he played that part, which ended in the sacrifice of his life, voluntarily or under compulsion?  Who, when all was said and done, had served as his accomplice or his executioner?

All these questions came crowding upon the minds of M. Desmalions and the others.  They thought of nothing but of how to solve them, and Don Luis could feel certain that his solution was accepted beforehand.  From that moment he had but to tell his story of what had happened without fear of contradiction.  He did so briefly, after the manner of a succinct report limited to essentials: 

“Three months before the crime, M. Fauville wrote a series of letters to one of his friends, M. Langernault, who, as Sergeant Mazeroux will have told you, Monsieur le Prefet, had been dead for several years, a fact of which M. Fauville cannot have been ignorant.  These letters were posted, but were intercepted by some means which it is not necessary that we should know for the moment.  M. Fauville erased the postmarks and the addresses and inserted the letters in a machine constructed for the purpose, of which he regulated the works so that the first letter should be delivered a fortnight after his death and the others at intervals of ten days.

“At this moment it is certain that his plan was concerted down to the smallest detail.  Knowing that Sauverand was in love with his wife, watching Sauverand’s movements, he must obviously have noticed that his detested rival used to pass under the windows of the house every Wednesday and that Marie Fauville would go to her window.

“This is a fact of the first importance, one which was exceedingly valuable to me; and it will impress you as being equal to a material proof.  Every Wednesday evening, I repeat, Sauverand used to wander round the house.  Now note this:  first, the crime prepared by M. Fauville was committed on a Wednesday evening; secondly, it was at her husband’s express request that Mme. Fauville went out that evening to go to the opera and to Mme. d’Ersinger’s.”