We were still watching them as they spoke to the guard, when I started and called the professor's attention to a tall, military-looking man who was hurrying along the platform. "That is the young man at the Silesian Embassy," I said. "He is evidently going back. Are we to see Mademoiselle Duplaix come along next?" "We are only concerned with Lanning for the present," Quarles answered, "and we have got to travel in the same carriage with him and Nixon. I expect they have tipped the guard to get a carriage to themselves. You must use your authority with him, Wigan, and show him that we are Scotland Yard men. Suggest that he put us into the carriage at the last moment with many apologies because there is no room elsewhere. In these disguises they will not recognize us." The two Englishmen and the Silesian did not approach each other, and apparently were quite ignorant of the fact that they were traveling by the same train. I made the necessary arrangements with the guard, and just as the train was starting we were bundled into the carriage, Quarles blowing and puffing in a most natural manner. "Sorry," he panted, speaking in broken English; "it is a train quite full, and I say to the man I must go. He put us in here. I am grieved to disturb you." Nixon said it didn't matter, but Lanning looked annoyed. Quarles talked to me chiefly about a wife he was returning to at Bohn. He became almost maudlin in his sentiment, and at intervals he raised his voice sufficiently to allow our traveling companions to overhear the conversation. Presently Quarles leaned towards me in a confidential manner, and said in a whisper which was intentionally loud enough for the others to hear: "From Bohn I go to Silesia to see the new flying machine." "What flying machine?" I asked. "Ah, it was a secret what Silesia have got hold of. It was wonderful. I myself tell you so, and I know. I--" "What do you know about it?" Lanning was leaning from his corner looking at Quarles. "Steady," said the professor. "If your hand does not from your pocket come in one blink of an eye you are a dead man. This is a big matter." Quarles had covered him with a revolver, and following his lead I covered Nixon. For a moment it was a tableau, not a sound nor a movement in the carriage. "As you say, it is a big matter," said Lanning, taking his hand from his pocket. He was for diplomacy rather than force, or perhaps he was a coward at heart. Nixon showed more courage and was quicker in his movements. His revolver was halfway out before I had slid along the seat and had my weapon at his head. "It is of no use," said Quarles. "It is not by accident we are here. We know, no matter how, but we know for certain that the plans of a wonderful aeroplane which cannot come to harm, and a model of it, are traveling by this train to-night. We came here to take them. We are sorry to disturb you, but it is necessary." Lanning laughed.