“Of course, I foresee that. You might meet the Mayhew girl or Whitehouse, or both coming down the staircase, and they would at once smell a rat. What about having a rehearsal of that excellent disguise which you are going to assume to-morrow? I can rig you out comfortably in a quarter of an hour.” Lydon agreed. There was an element of sport in the whole thing which the hatchet-faced detective seemed to enjoy as much as his client. Disguised in a heavy beard and moustache, the young man walked out of the detective’s office. They took a taxi and dismounted within a few yards of Ashstead Mansions. The porter, a young military-looking man, was standing outside the particular block they entered. Grewgus whispered in his companion’s ear. “I’ve reckoned him up in a single glance. I know the type. He will talk till doomsday after the first ten-shilling note is slipped in his hand. Of course, you won’t mind a bit of expense over the job?” Lydon whispered back that, under the circumstances, expense was no object. He was prepared to spend a considerable amount of money to confirm or disprove his suspicions of Zillah Mayhew. They went into the hall, and scrutinized the board containing the names of the particular block in which Number 18 was situated. The name of Whitehouse did not figure on it. The detective rubbed his thin face. “This is 18 Ashstead Mansions, right enough, but nobody of the name of Whitehouse resides here. You are quite sure of the number?” The young man smiled. Detectives perhaps resembled solicitors; they did not credit the average person with ordinary intelligence. “Impossible for me to make a mistake,” he answered. “I was far too interested not to make sure. I only learned it last night.” Seeing they were obviously perplexed, the porter strolled up to them. “Are you looking for somebody, sir?” he asked, addressing Grewgus, whom he evidently regarded as the more dominant personality of the two. “Perhaps I can assist you.” Grewgus spoke in his rather precise, formal way. “Am I correct in saying that a Mr. Whitehouse occupies one of these flats?” The military-looking man shook his head. “Nobody of that name in this block, sir, or any of the others.” Grewgus turned to his companion with a finely simulated air of surprise. “Either we have been misinformed as to the precise locality or the name itself,” he said. Lydon, not used to the subtle processes of the detective mind, thought it best to say as little as possible. He just muttered the safe words, “It certainly looks like it, doesn’t it?” playing up to the lead given him by the astute Grewgus. That gentleman extracted with a great air of deliberation a ten-shilling note from his waistcoat pocket and pressed it into the receptive hand of the porter. “I may as well tell you we are here to make a few inquiries about a certain party,” he said. “You say there is no Mr. Whitehouse here. Does a young lady named Mayhew reside in this or any of the other blocks?”