Humblethorne flushed at this direct blow. “I have proof of things that will need a good deal of explanation,” he said shortly. “You shall have all the explanation you require—in half an hour,” she said. “Delay the arrest that length of time and you will have no reason to regret it.” “What do you mean?” he exclaimed. “You have been looking for a pair of evening shoes, I think,” she went on with apparent irrelevance. “Yes.” He tried unsuccessfully to hide his eagerness. “I will show you them—in half an hour. Wait that long at any rate.” She nodded and went into the dining-room. CHAPTER XIII How it Happened With a heart beating with excitement Evelyn opened the door that led from the dining-room into the pantry. Luck favoured her, for Fairlie was in there alone. “Oh, Fairlie,” she said in the most natural voice she could assume, “I’m so thirsty; can you give me a glass of water?” As he went to fetch it her mind was in a ferment. She had promised to explain everything in half an hour, but could she? There was much she could only guess even if her deductions all proved to be facts; and it suddenly crossed her mind that, if the finger-marks on the pedestal did not prove to be Fairlie’s, she was as far from the truth as ever. At any rate, she had come to a point when she must share all her discoveries with Humblethorne. Fairlie now returned with a glass of water on a small silver tray. She took the latter carefully by the opposite side; then, wishing to duplicate his finger-prints in case of failure, she said, “That looks a little dusty, Fairlie,” and lifted the tray towards him. Unsuspectingly he took the glass, held it up against the light, and then set it down again on the tray. “It looks all right to me, Miss Evelyn; but I’ll get you another,” he replied. “Oh no, don’t trouble,” she exclaimed, and bore away tray and glass. As she passed through the hall again she was very conscious of the curious, not to say suspicious, gaze of the two men; but she was too intent on her purpose, and that purpose held too much that was terrible, for her to feel the amusement which would otherwise have been hers. Without looking at them she carried her last evidence carefully upstairs. “Well,” remarked Birts with a heavy sigh as she disappeared, “I wonder what she’s up to now: play acting, I call it.” Humblethorne did not reply, though his thoughts were running in the same direction. He was uneasy; it was difficult to stifle altogether the conviction that this girl, whose quick brain and perceptive eye had already aroused his appreciation, would not speak so confidently unless she had something better than a mere belief to go upon. He was moodily pacing the hall when Evelyn came downstairs again. “I am ready now,” she said. “I asked for half an hour, but it did not take so long.” “Perhaps you will be good enough to explain your mysteries, then,” remarked Humblethorne with slight irony.