She picked up a small latch-key from the desk. "This is number 11, isn't it?" she asked quickly. "No! Number 11 is the flat immediately overhead," he told her. She appeared unconvinced. "But I opened the door with this key," she declared. "Mr. Barnes and I have similar locks," he said. "The fact remains that this is number 9, and number 11 is one story overhead." She drew a long breath, presumably of relief, and moved a step forward. "I am very sorry!" she declared. "I have made a mistake. You must please accept my apologies." He stood motionless in front of the door. He was pale, clean-shaven, and slim, and in his correct evening clothes he seemed a somewhat ordinary type of the well-bred young Englishman. But his eyes were grey, and his mouth straight and firm. She came to a standstill. Her eyes seemed to be questioning him. She scarcely understood his attitude. "Kindly allow me to pass!" she said coldly. "Presently!" he answered. Her veil was still raised, and the flash of her eyes would surely have made a weaker man quail. But Wrayson never flinched. "What do you mean by that?" she demanded. "I have explained my presence in your room. It was an accident which I regret. Let me pass at once." "You have explained your presence here," he answered, "after a fashion! But you have not explained what your object may be in making use of that key to enter Mr. Barnes' flat. Are you proposing to subject his belongings to the same inspection as mine?" he asked, pointing to his disordered desk. "My business with Mr. Barnes is no concern of yours!" she exclaimed haughtily. "Under ordinary circumstances, no!" he admitted. "But these are not ordinary circumstances. Forgive me if I speak plainly. I found you engaged in searching my desk. The presumption is that you wish to do the same thing to Mr. Barnes'." "And if I do, sir!" she demanded, "what concern is it of yours? How do you know that I have not permission to visit his rooms--that he did not himself give me this key?" She held it out before him. He glanced at it and back into her face. "The supposition," he said, "does not commend itself to me." "Why not?" He looked at the clock. "You see," he declared, "that it is within a few minutes of midnight. To be frank with you, you do not seem to me the sort of person likely to visit a bachelor such as Mr. Barnes, in a bachelor flat, at this hour, without some serious object."