A glance at the window showed him that it was impossible for the inmates of the room to have escaped that way. Presently the clothes were heaped on the floor, and the detectives were attacking the wooden back of the wardrobe, which did, in fact, prove to be a door leading into the next house. Whilst they were so engaged, Dick made a scrutiny of the table, which was littered with papers. He saw something and called Elk. “What is this, Elk?” The detective took the four closely-typed sheets of paper from his hand. “Mills’ confession,” he said in amazement. “There are only two copies, one of which I have, and the other is in the possession of your department, Captain Gordon.” At this moment the wardrobe backing was smashed in, and the detectives were pouring through to the next house. And then it was that they made the interesting discovery that, to all intents and purposes, communication was continuous between a block of ten houses that ran to the end of the street. And they were not untenanted. Three typical Frogs occupied the first room into which they burst. They found others on the lower floor; and it soon became clear that the whole of the houses comprising the end block had been turned into a sleeping-place for the recruits of Frogdom. Since any one of these might have been No. 7, they were placed under arrest. All the communicating doors were now opened. Except in the case of Maitland’s house, no attempt had been made to camouflage the entrances, which in the other houses consisted of oblong apertures, roughly cut through the brick party walls. “We may have got him, but I doubt it,” said Elk, coming back, breathless and grimy, to where Dick was examining the remainder of the documents which he had found. “I haven’t seen any man who looks like owning brains.” “Nobody has escaped from the block?” Elk shook his head. “My men are in the passage and the street. In addition, the uniformed police are here. Didn’t you hear the whistle?” Elk’s assistant reported at that moment. “A man has been found in one of the back yards, sir,” he said. “I’ve taken the liberty of relieving the constable of his prisoner. Would you like to see him?” “Bring him up,” said Elk, and a few minutes later a handcuffed man was pushed into the room. He was above medium height; his hair was fair and long, his yellow beard was trimmed to a point. For a moment Dick looked at him wonderingly, and then: “Carlo, I think?” he said. “Hagn, I’m sure!” said Elk. “Get those whiskers off, you Frog, and we’ll talk numbers, beginning with seven!” Hagn! Even now Dick could not believe his eyes. The wig was so perfectly made, the beard so cunningly fixed, that he could not believe it was the manager of Heron’s Club. But when he heard the voice, he knew that Elk was right. “Number Seven, eh?” drawled Hagn. “I guess Number Seven will get through your cordon without being challenged, Mr. Elk. He’s friendly with the police. What do you want me for?”