“It’s all right, Alec,” said Barbara gently. “It was a perfectly reasonable mistake to make. As I said, that was only a dreadful coincidence.” “And aren’t you going to change your mind about what you said this morning?” asked Alec humbly. Barbara looked at him quickly. “Why should I?” she returned swiftly. “I mean——” She hesitated and corrected herself. “Why should you think I might?” “I don’t know. You were very upset this morning, and it occurred to me that you might have had bad news and were acting on the spur of the moment; and perhaps when you had thought it over, you might——” He broke off meaningly. Barbara seemed strangely ill at ease. She did not reply at once to Alec’s unspoken question, but twisted her wisp of a handkerchief between her fingers with nervous gestures that were curiously out of place in this usually uncommonly self-possessed young person. “Oh, I don’t know what to say,” she replied at last, in low, hurried tones. “I can’t tell you anything at present, Alec. I may have acted too much on the spur of the moment. I don’t know. Come and see me when we get back from the Mertons’ next month. I shall have to think things over.” “And you won’t tell me what the trouble was, dear?” “No, I can’t. Please don’t ask me that, Alec. You see, that isn’t really my secret. No, I can’t possibly tell you!” “All right. But—but you do love me, don’t you?” Barbara laid her hand on his arm with a swift, caressing movement. “It wasn’t anything to do with that, old boy,” she said softly. “Come and see me next month. I think—I think I _might_ have changed my mind again by then. No, Alec! You mustn’t! Anyhow, not here of all places. Perhaps I’ll let you once—just a tiny one!—before we go; but not unless you’re good. Besides, I’ve got to run in and pack now. We’re catching the two forty-one, and Mother will be waiting for me.” She gave his hand a sudden squeeze and turned towards the house. “That was a bit of luck, meeting her out here!” murmured Alec raptly to himself as he watched her go. Wherein he was not altogether correct in his statement of fact; for as the lady had come into the garden for that express purpose, the subsequent meeting might be said to be due rather to good generalship than good luck. It was therefore a remarkably jubilant Watson who returned blithely to the library to find his Sherlock sitting solemnly in the chair before the big writing table and staring hard at the chimney-piece. In spite of himself he shivered slightly. “Ugh, you ghoulish brute!” he exclaimed. Roger looked at him abstractedly. “What’s up?” “Well, I can’t say that I should like to sit in that particular chair just yet awhile.” “I’m glad you’ve come back,” Roger said, rising slowly to his feet. “I’ve just had a pretty curious idea, and I’m going to test it. The chances are several million to one against it coming off, but if it _does_——! Well, I don’t know what the devil we’re going to do!”