"The writing of the man who alone knows where Marx is," I answered. "It is he who calls for his letters and forwards them." "His name? I insist upon knowing his name." "de Cartienne." My father's face turned a shade paler and his eyebrows contracted. "You have been keeping this from me, Philip. You shall not go near that man. I forbid it. My God! Marx and de Cartienne friends!" He stopped short on the pavement and looked at me with a new light in his face. He began to understand. "Marx and de Cartienne," he repeated slowly. "Philip, cannot you see what this means? Marx has been de Cartienne's tool and I have been their victim. Where is de Cartienne? Philip, you shall tell me! Do you hear?" My father seized my arm and held it fast. I turned and faced him. "Father, you must leave this to me," I said, firmly. "I have thought it all over in the train and my plans are made. You will trust me?" "Tell me what they are," he said. "I have in my possession a box belonging to de Cartienne, which contains a secret. Until I yield that box up to him I am safe, since he can only get it from me. You see that he tells me in this note to bring it with me." "Yes. Go on." "Well, I am going without the box, and if he is really ignorant of who I am and willing to give me the information about Marx, why, then I can easily come back for it, and whatever it contains he must have unopened. "If, on the other hand, I fall into any sort of trap and he makes me send for it, then, immediately on receipt of my message, no matter how it is couched, you must force the box open, and if it contains anything in the least suspicious, come straight to my aid with the police. The messenger who comes for the box must be bribed or frightened into bringing you." "I do not like it, Philip. It is all too roundabout. If de Cartienne has any idea who you are, you are running a risk." "I don't think so," I answered. "Until he gets possession of that box he will feel himself, to a certain extent, in my hands and will not be likely to do me an injury." "What do you suppose the box contains?" I hesitated and looked around. de Cartienne's servant was some distance off and there was no one within hearing. "Have you read the newspapers just lately?" I asked. My father shook his head. "Only the literary newspapers." I bought a special edition, which a newsboy was brandishing in our faces, and, turning down the leading article, passed it on to my father. He glanced down at it and then looked up at me in blank amazement. "Philip, you cannot mean this!" he exclaimed. "Why not?" I answered. "I do, indeed; but whether there is anything in it or not we shall soon know. I must go now. You understand what to do if I send for the box." "I don't like your expedition at all," he said, doubtfully. "Have you any idea where you are going?" I shook my head.