“Well?” said Alec tolerantly. “What is it now?” “If you come here, Alec,” said Roger, very gently, “I’ll show you how the murderer got away last night.” Chapter XIII Mr. Sheringham Investigates a Footprint “Show me _what_?” Alec exclaimed, bounding out of his chair. “How the murderer escaped,” Roger repeated, turning and smiling happily at his dumb-founded accomplice. “It’s extraordinarily simple, really. That’s why we never spotted it. Have you ever noticed, Alec, that it’s always the simple things of life—plans, inventions, what you like—that are the most effective? Take, for instance——” Alec seized his too voluble friend by the shoulder and shook him violently. “_How_ did the chap escape?” he demanded. Roger pointed to the window through which he had been leaning. “There!” he said simply. “Yes, but how do you know?” cried the exasperated Alec. “Oh, is that what you meant? Come, friend Alec.” Roger took his fellow-sleuth by the arm and pointed triumphantly to the window-sill. On the surface of the white paint were a few faint scratches. “You see those? Now look at that!” And he indicated something on the flower bed beneath. “I said it must be lying under our noses all the time,” he added complacently. Alec leaned out of the window and looked at the bed. Just below the window was an unmistakable footprint, the toe pointing towards the window. “You said _escaped_, didn’t you?” he asked, withdrawing his head. “I did, Alexander.” “Well, I’m sorry to disappoint you and all that,” said Alec, in a tone that curiously belied his words, “but nobody escaped this way. Someone got in. If you look again, carefully this time, you’ll see that the toe is pointing towards the window; not the heel. That means that somebody stepped from the ground to the window-ledge, not _vice versa_.” “Alec, you are on your day to-day, aren’t you?” said Roger admiringly. “Precisely the same thought occurred to myself at a first glance. Then, looking carefully, as you so kindly suggest, I noticed that the indentation of the heel is very much deeper than that of the toe, indicating that somebody stepped backwards from the window to the ground, after thoughtfully closing the window behind him. If he’d been stepping up, the toe would be deeper than the heel, as a moment’s thought will show you, won’t it?” “Oh!” said the crestfallen Alec. “Sorry to have to score off you in that blatant Sherlockian way,” Roger continued more kindly, “but you did ask for it, you know. No, but seriously, Alec, this is most extraordinarily important. It clears up the last difficulty about murder.” “But how did he close the window behind him?” asked Alec, still half incredulous.