His mind switched over to the case itself. He felt the probability of Felix’s guilt had been somewhat strengthened. Mr. Gordon’s statement was entirely consistent with that hypothesis. One would naturally expect the journey to be carried out just as it had been. In Paris, the lovers would be careful not to be seen together. At a station like the Gare du Nord, where acquaintances of both might easily be present, they would doubtless ignore each other’s existence. On the boat they would probably risk a conversation, particularly as the deck was almost deserted owing to the weather, but in London, especially if Felix expected some one to meet him, they would follow their Paris plan and leave the station separately. Yes, it certainly worked in. The Inspector lit one of his strong cigars and gazed with unseeing eyes at the flying landscape as he continued his ruminations. On arrival in London what would be their next step? Felix, he expected, would shake off his friend, meet Madame at some prearranged spot, and in all probability take her to St. Malo. Then he recalled that the housekeeper had been granted a holiday, and they would doubtless arrive to find a house without food or fire, empty and cheerless. Therefore would they not go to an hotel? He thought it likely, and he began to plan a possible future step, a visit to all the probable hotels. But while speculating on the best to begin with, it occurred to him that if Felix had really committed the murder, it must, almost certainly, have been done at St. Malo. He could not conceive it possible at a hotel. Therefore probably they did go to the villa after all. He went a step further. If the murder had taken place at St. Malo, the cask must have been packed there. He recalled the traces this operation had left in Boirac’s study. Surely some similar indications must have been left at the villa? If the cask had stood on a carpet or even possibly a linoleum, he might expect marks of the ring. And if not, there was the sawdust. He did not believe every trace of sawdust could have been removed. It had been his intention in any case to search the house, and he took a mental note when doing so to look with special care for any such traces. This search, he decided, should be his next business. On the following morning, therefore, he set out for St. Malo with his assistant, Sergeant Kelvin. As they drove, he explained the theory about the unpacking of the cask, and pointed out what, if this had been done, they might expect to find. The house was empty as, owing to Felix still being in the hospital, the housekeeper’s leave had been extended. Burnley opened the door with a key from Felix’s bunch and the two men entered.