“Remain on duty at the station until I send and relieve you,” he said. “There are several special trains to Cannes and Monte Carlo about three o’clock on account of the ball. Be careful to catch them all. It is my opinion that he may be going to cross the frontier at Ventimiglia. I’ll telephone there as soon as I get down to the bureau.” “Bien, m’sieur,” answered the other, and as they went out, wishing me good-night, I followed them, asking of the senior of the pair,-- “Tell me, m’sieur, what should be my best course of action. Do you think the threats are serious?” “Not at all,” he answered reassuringly. “My dear mademoiselle, don’t distress yourself in the very least regarding what he has said. He has only endeavored to frighten you into rendering him assistance. Act just as you think proper. Your experience to-night has certainly been a strange one; but if I were in your place I would return to the hotel, sleep soundly, and forget it all until--well, until we make an arrest.” “You expect to do so, then?” “We, of course, hope so. In my profession, you know, everything is uncertain. So much depends upon chance,” and he smiled pleasantly. “Then I presume you will communicate with me later as to the further result of your investigations?” I suggested. “Most certainly. Mademoiselle shall be kept well informed of our operations, never fear.” We were at the door of the Casino, where a great crowd had assembled to watch the maskers emerging. “Shall I call you a fiacre?” he asked quite gallantly. “No, thank you,” I responded. “I’ll walk. It’s only a few steps to the Grand.” “Ah, of course,” he laughed. “I had forgotten. Bon soir, mademoiselle.” I wished him good-night, and next second he was lost in the crowd, while with my mind full of my extraordinary adventure I walked along the Quai St. Jean Baptiste to the hotel. The incidents had been so strange that they seemed beyond belief. I found the faithful Felicita dozing, but Ulrica had not returned. When she entered, however, a quarter of an hour later, she was in the highest of spirits, declaring that she had experienced a most delightful time. “My opinion of the Carnival ball, my dear, is that it is by far the jolliest function on the Riviera,” she declared. Then in the same breath she proceeded to give me an outline of her movements from the time we were lost to one another in the crowd. She had, it appeared, had supper with Gerald and several friends, and the fun had been fast and furious. Her dress was badly torn in places, and certainly her dishevelled appearance showed that she had entered thoroughly into the boisterous merriment of the Carnival. “And you?” she inquired presently. “What in the world became of you? We searched everywhere before supper, but couldn’t find you.” “I met a rather entertaining partner,” I responded briefly. “A stranger?” “Yes,” and I gave her a look by which she understood that I intended to say nothing before Felicita.