The detective twisted his moustache, eyeing my friend in a somewhat bantering fashion. “You don’t agree with me, eh? Well, what strikes you particularly about the case. Let’s hear your views.” “One thing presents itself to me as being significant. Tell me, M. Giraud, does nothing strike you as familiar about this case? Is there nothing it reminds you of?” “Familiar? Reminds me of? I can’t say off-hand. I don’t think so, though.” “You are wrong,” said Poirot quietly. “A crime almost precisely similar has been committed before.” “When? And where?” “Ah, that, unfortunately, I cannot for the moment remember—but I shall do so. I had hoped you might be able to assist me.” Giraud snorted incredulously. “There have been many affairs of masked men! I cannot remember the details of them all. These crimes all resemble each other more or less.” “There is such a thing as the individual touch.” Poirot suddenly assumed his lecturing manner, and addressed us collectively. “I am speaking to you now of the psychology of crime. M. Giraud knows quite well that each criminal has his particular method, and that the police, when called in to investigate—say a case of burglary—can often make a shrewd guess at the offender, simply by the peculiar method he has employed. (Japp would tell you the same, Hastings.) Man is an unoriginal animal. Unoriginal within the law in his daily respectable life, equally unoriginal outside the law. If a man commits a crime, any other crime he commits will resemble it closely. The English murderer who disposed of his wives in succession by drowning them in their baths was a case in point. Had he varied his methods, he might have escaped detection to this day. But he obeyed the common dictates of human nature, arguing that what had once succeeded would succeed again, and he paid the penalty of his lack of originality.” “And the point of all this?” sneered Giraud. “That when you have two crimes precisely similar in design and execution, you find the same brain behind them both. I am looking for that brain, M. Giraud—and I shall find it. Here we have a true clue—a psychological clue. You may know all about cigarettes and match ends, M. Giraud, but I, Hercule Poirot, know the mind of man!” And the ridiculous little fellow tapped his forehead with emphasis. Giraud remained singularly unimpressed. “For your guidance,” continued Poirot, “I will also advise you of one fact which might fail to be brought to your notice. The wrist watch of Madame Renauld, on the day following the tragedy, had gained two hours. It might interest you to examine it.” Giraud stared. “Perhaps it was in the habit of gaining?” “As a matter of fact, I am told it did.” “_Eh bien___, then!” “All the same, two hours is a good deal,” said Poirot softly. “Then there is the matter of the footprints in the flower-bed.” He nodded his head towards the open window. Giraud took two eager strides, and looked out. “This bed here?” “Yes.”