Sospel is a picturesque little city lost between the last counterfores of the Alps, two hours and a half from Mentone by coach. No railroad passes through there. It is one of the most retired and quietest corners of France, the most dreaded by revenue officers and by the Alpine hunters. But the road which leads to it is one of the most beautiful in the world, for, in order to reach Sospel, it is necessary to wind through I do not know how many mountain passes, to climb countless precipices, and to follow, until one reaches Castillon, the deep and narrow valley of Carei, as wild as a field in Judæa, but covered with luxuriant herbage, bright with beautiful flowers, fertile and beautiful with the shimmering gold of its forests of olive trees, which descend from the heights to the clear bed of the stream by the terraces of a giant staircase formed by nature. I had been at Sospel a few years previously with a party of English tourists in an immense carriage, drawn by eight horses, and I had brought from the trip a remembrance of vertigo which came over my mind in the future every time the name was mentioned. Why was Brignolles going to Sospel? I must find out. The diligence was crowded and had already started on its way with a loud noise of creaking springs and of shaking window panes. I hired a carriage from the station and in a few moments I, too, was climbing over the rocks to the valley of Carei. How I regretted not having spoken of my telegram to Rouletabille! The strange behavior of Brignolles would have given him ideas, useful and reasonable, while, for my part, I had not the slightest idea of how to reason. I only knew how to follow this Brignolles as a dog follows his master or a policeman follows his quarry by the clues which he finds. And yet, had I followed them well, these clues? It was at the moment that I felt certain that nothing in the world in regard to this man’s movements could be small enough to escape me that I made a formidable discovery. I had let the diligence keep a little way in advance, a precaution which I deemed necessary, and I reached Castillon ten minutes later than Brignolles. Castillon is at the highest point of the road between Mentone and Sospel. My driver asked my permission to let his horse rest for a moment, and while he watered the beast, I descended from the carriage, and, at the entrance of a tunnel through which it was necessary to pass to reach the opposite turn of the mountain, I beheld Brignolles and Frederic Larsan!