"You see," he went on, "that one--this--is different from the rest. It has retained its original form better, and has been less broken, because of being of thicker paper. It is a crumpled envelope. Look at the flap--it has never been closed down. Moreover, on that same flap you may read in embossed letters, still visible, part of the name of this house. Plain inference--this was an envelope intended for a letter never sent, and so crumpled up and dropped into the waste-paper basket. But why should such an apparently unimportant thing as that be carefully brought from the waste-paper basket and burnt? Somebody was anxious that the smallest scrap of paper evidencing a certain correspondence should be destroyed. But look closely at the front of the envelope--the ink shows a rather lighter grey than the paper. The address is incomplete--at any rate, no more than some of the first line and a little of the second is at all visible now; but it is plain that the first line begins with an E. The letters immediately following are not distinct, but next there is a capital M beginning a name which is clearly Myatt or Myall. Now, _that_ is why, when Myatt came here, I took the first steps to hand to get an impression of his finger-tips, in order to compare them with the marks on that paper." "But why," asked the astonished rector, "why did he come back?" "Nothing but a bold measure to see how things were going--he came as his own spy, that's all. He's a keen and dangerous man. Don't you remember telling me how he called on you yesterday, though you hardly knew him by sight, merely to ask you to persuade Mason to take a holiday? It struck me as a little odd at the time. He was pumping you, Mr. Potswood--he wanted to find what Mason had been saying! And he is not alone--plainly he is not alone, for poor Mason knew they were watching everywhere. But come--this is no time for speculation. Plummer--you must hold him safely--we'll pick up evidence enough when you've got him. I wouldn't leave it, Plummer--I'd take him to-night!" "You're right--right, as usual, Mr. Hewitt," Plummer agreed. "More especially as the rector was--well, a little incautious in talking to him just now." "I? What did I say?" Mr. Potswood asked, astonished. "I had no suspicions--how could I have----" "No, Mr. Potswood," the detective replied, "you had no suspicions, and for that very reason, in the excitement of the narrative, you called Mr. Martin Hewitt by his right name at least twice! And after I had called him 'doctor,' too!" he added regretfully. "Is that so?" asked Hewitt. The poor rector was sadly abashed. "But I really wasn't aware of it, Mr. Hewitt!" he protested. "I hardly think I could--but, there, perhaps I did! Of course, if Inspector Plummer remembers it----"