“I do not know,” he answered. “It hath been in the blood for a century. It started, I have heard, in some absurd question of precedence. It is the old story of the frog and the mouse who found it impossible to dwell in peace together. If Roquefort hath sacked Cadillac, there will be some merry work ere we return to Montauban.”

I smiled, for this was my first campaign, and it pleased me mightily. Besides, I had not only to win my spurs, but to prove also to M. le Comte that I was no liar.

“Monsieur,” I said, “permit me to assure you that you will have no cause to watch me. I am too anxious to see this expedition through. My honor is at stake, and I mean to prove that it is not I but another who is the traitor. But tell me something of the Vicomte d’Aurilly. How comes he in this household?”

I could feel my companion’s eyes searching my face, but I did not meet his gaze, fearing that he might read my thought.

“The Vicomte d’Aurilly,” he said quietly at last, “belongs to one of the oldest families of the Basses Pyrenees. Unhappily, the fortunes of his house have declined greatly, but this has not lessened his pride, as you may have perceived. He is in this household because he is a suitor for the hand of Mademoiselle Valérie, only daughter of M. le Comte.”

For a moment I saw my theory falling into bits. If d’Aurilly were a suitor for Mademoiselle, why should he seek to betray her into Roquefort’s hands?

“Only,” added my companion, in a lower tone and with a certain look that drew from me a second glance, “I believe he is an unsuccessful suitor. It is said that M. le Comte had the goodness to consult his daughter in the matter and that she would have none of it.”

Well, that was different—that gave me the key to d’Aurilly’s motive! There was a tone in my companion’s voice which drew my eyes again to his face—he was staring at the table before him, distraught, seeing nothing. It seemed to me that I could read his secret, and of a sudden I determined to tell him my theory. I glanced around and saw that the room was almost empty.

“M. de Fronsac,” I began, “for what I am about to tell you I have no proof, yet I believe myself not far beside the mark. And first let me assure you on my honor that I am what I claim to be, Paul de Marsan, liege to M. le Comte, and that I brought a message to him. That message was stolen from me, as you have heard. I believe, Monsieur, that d’Aurilly was the thief.”

My companion started round upon me, all his blood in his face.