"No, thanks," he said; "I only polish a good apple, never peel it. It's a mistake, except with thick-skinned foreign ones." And he began to munch the apple as only a boy or a healthy athlete can. Presently he turned his head to order coffee. The waiter's back was turned, and he had to be called twice. To my unutterable amazement Hewitt reached swiftly across the table, snatched the half-eaten apple from the young man's plate and pocketed it, gazing immediately, with an abstracted air, at a painted Cupid on the ceiling. Our neighbor turned again, looked doubtfully at his plate and the table-cloth about it, and then shot a keen glance in the direction of Hewitt. He said nothing, however, but took his coffee and his bill, deliberately drank the former, gazing quietly at Hewitt as he did it, paid the latter, and left. Immediately Hewitt was on his feet and, taking an umbrella, which stood near, followed. Just as he reached the door he met our late neighbor, who had turned suddenly back. "Your umbrella, I think?" Hewitt asked, offering it. "Yes, thanks." But the man's eye had more than its former hardness, and his jaw muscles tightened as I looked. He turned and went. Hewitt came back to me. "Pay the bill," he said, "and go back to your rooms; I will come on later. I must follow this man--it's the Foggatt case." As he went out I heard a cab rattle away, and immediately after it another. I paid the bill and went home. It was ten o'clock before Hewitt turned up, calling in at his office below on his way up to me. "Mr. Sidney Mason," he said, "is the gentleman the police will be wanting to-morrow, I expect, for the Foggatt murder. He is as smart a man as I remember ever meeting, and has done me rather neatly twice this evening." "You mean the man we sat opposite at Luzatti's, of course?" "Yes, I got his name, of course, from the reverse of that gold medal he was good enough to show me. But I fear he has bilked me over the address. He suspected me, that was plain, and left his umbrella by way of experiment to see if I were watching him sharply enough to notice the circumstance, and to avail myself of it to follow him. I was hasty and fell into the trap. He cabbed it away from Luzatti's, and I cabbed it after him. He has led me a pretty dance up and down London to-night, and two cabbies have made quite a stroke of business out of us. In the end he entered a house of which, of course, I have taken the address, but I expect he doesn't live there. He is too smart a man to lead me to his den; but the police can certainly find something of him at the house he went in at--and, I expect, left by the back way. By the way, you never guessed that simple little puzzle as to how I found that this _was_ a murder, did you? You see it now, of course?" "Something to do with that apple you stole, I suppose?"