“Meanwhile, the train is steaming on, and you must do something; you must get on with the murder. Is he in the same carriage, or in a different one? And if it’s a different one, is there a corridor between? Let’s see, there’s a corridor on the three o’clock train, but it doesn’t connect with the slip that comes off at Binver. Probably you are in the Binver slip, because the railway people always try to shove one into that. I am sure you were in the slip, not in the corridor part of the train, because later on you are going to execute certain complicated manœuvres over a dead man’s body, and it would be dangerous to do that if a man might look in and say ‘Tickets please’ at any moment. No, you must be in the slip, and unless you are in the same carriage, there is no connection between you and him except along the footboard. That is rather hard to climb along while the train is going; but of course in the fog it may not be going just at this moment. It may be being held up by those signals that are connected with the Paston Whitchurch goods siding, those you see over there—at least, no, you do not see them because of the fog. “But are you in the same carriage? You might have the decency to tell me that. Preferably not, because people saw you getting in, and people might remember afterwards that you got into the same carriage with him. Besides, you are choosing for the murder a part of the line where it curves, and curves away from the side where you are going to throw the man out. Why did you choose that particular part, unless you wanted to do something in the way of climbing along the footboard? I think you are in a different carriage. And you’ve got to murder somebody who is next door. Now, it’s no good telling me that you’re going to climb along the footboard and attack him, because he would certainly ring the communication cord if you did. “He is alone in his first-class carriage, and you are alone in yours. Possibly he is asleep, but if so you’ve no means of knowing. You might, of course, bore a hole between the two carriages—and then? Put a cobra through, like the Speckled Band, to make him jump out of the train, or to kill him as he sits there? Not very probable, I think; cobras are so difficult to buy, as you rightly observe, without attracting suspicion. Or could you let loose some poisonous gas through the hole? That is a really bright idea; I give you 90 per cent. for it, only I hardly think a very practicable solution, my dear Reeves, if you don’t mind my saying so. You would look such a fool getting into the train with a couple of oxygen cylinders, or a large balloon. No, you can’t do anything with holes in the partition. To do anything, you must be leaning out of the window. If anything is to be done, you must both be leaning out of the window.