Hewitt produced the stick. It was an ordinary, thick Malacca cane, with a buckhorn handle and a silver band. Hewitt bent it across his knee, and laid it on the table. "Yes," Dixon answered, "that is Ritter's stick. I think I have often seen it in the stand. But what in the world----" "One moment; I'll just fetch the stick Mirsky left behind." And Hewitt stepped across the corridor. He returned with another stick, apparently an exact facsimile of the other, and placed it by the side of the other. "When your assistants went into the inner room, I carried this stick off for a minute or two. I knew it was not Worsfold's, because there was an umbrella there with his initial on the handle. Look at this." Martin Hewitt gave the handle a twist, and rapidly unscrewed it from the top. Then it was seen that the stick was a mere tube of very thin metal, painted to appear like a Malacca cane. "It was plain at once that this was no Malacca cane--it wouldn't bend. Inside it I found your tracings, rolled up tightly. You can get a marvellous quantity of thin tracing-paper into a small compass by tight rolling." "And this--this was the way they were brought back!" the engineer exclaimed. "I see that, clearly. But how did they get away? That's as mysterious as ever." [Illustration: "HEWITT PRODUCED THE STICK."] "Not a bit of it. See here. Mirsky gets hold of Ritter, and they agree to get your drawings and photograph them. Ritter is to let his confederate have the drawings, and Mirsky is to bring them back as soon as possible, so that they shan't be missed for a moment. Ritter habitually carries this Malacca cane, and the cunning of Mirsky at once suggests that this tube should be made in outward facsimile. This morning, Mirsky keeps the actual stick and Ritter comes to the office with the tube. He seizes the first opportunity--probably when you were in this private room, and Worsfold was talking to you from the corridor--to get at the tracings, roll them up tightly, and put them in the tube, putting the tube back into the umbrella stand. At half-past twelve, or whenever it was, Mirsky turns up for the first time with the actual stick and exchanges them, just as he afterwards did when he brought the drawings back." "Yes, but Mirsky came half an hour after they were--oh, yes, I see. What a fool I was! I was forgetting. Of course, when I first missed the tracings they were in this walking-stick, safe enough, and I was tearing my hair out within arm's reach of them!" "Precisely. And Mirsky took them away before your very eyes. I expect Ritter was in a rare funk when he found that the drawings were missed. He calculated, no doubt, on your not wanting them for the hour or two they would be out of the office." "How lucky that it struck me to jot a pencil-note on one of them! I might easily have made my note somewhere else, and then I should never have known that they had been away."