“If The Walled House,” he said at last, “is so carefully guarded that Sir Timothy has been informed of my watching the place and has been made aware of my mild questionings, it must be because there is something to conceal. I may or may not be on the track of Mr. Reginald Wilmore, but,” the detective concluded, “of one thing I am becoming convinced--The Walled House will pay for watching.” CHAPTER XXI It was a day when chance was kind to Francis. After leaving his rooms at the Temple, he made a call at one of the great clubs in Pall Mall, to enquire as to the whereabouts of a friend. On his way back towards the Sheridan, he came face to face with Margaret Hilditch, issuing from the doors of one of the great steamship companies. For a moment he almost failed to recognise her. She reminded him more of the woman of the tea-shop. Her costume, neat and correct though it was, was studiously unobtrusive. Her motoring veil, too, was obviously worn to assist her in escaping notice. She, too, came to a standstill at seeing him. Her first ejaculations betrayed a surprise which bordered on consternation. Then Francis, with a sudden inspiration, pointed to the long envelope which she was carrying in her hand. “You have been to book a passage somewhere!” he exclaimed. “Well?” The monosyllable was in her usual level tone. Nevertheless, he could see that she was shaken: “You were going away without seeing me again?”' he asked reproachfully. “Yes!” she admitted. “Why?” She looked up and down a little helplessly. “I owe you no explanation for my conduct,” she said. “Please let me pass.” “Could we talk for a few minutes, please?” he begged. “Tell me where you were going?” “Oh, back to lunch, I suppose,” she answered. “Your father has been up, looking for you,” he told her. “I telephoned to The Sanctuary,” she replied. “He had just left.” “I am very anxious,” he continued, “not to distress you, but I cannot let you go away like this. Will you come to my rooms and let us talk for a little time?” She made no answer. Somehow, he realised that speech just then was difficult. He called a taxi and handed her in. They drove to Clarges Street in silence. He led the way up the stairs, gave some quick orders to his servant whom he met coming down, ushered her into his sitting-room and saw her ensconced in an easy-chair. “Please take off that terrible veil,” he begged. “It is pinned on to my hat,” she told him. “Then off with both,” he insisted. “You can't eat luncheon like that. I'm not going to try and bully you. If you've booked your passage to Timbuctoo and you really want to go--why, you must. I only want the chance of letting you know that I am coming after you.” She took off her hat and veil and threw them on to the sofa, glancing sideways at a mirror let into the door of a cabinet. “My hair is awful,” she declared: He laughed gaily, and turned around from the sideboard, where he was busy mixing cocktails.