“What are your grounds for arresting him?” “Do you expect me to give them to you?” “As a matter of courtesy, yes.” Giraud looked at him doubtfully. He was torn between a desire to refuse rudely and the pleasure of triumphing over his adversary. “You think I have made a mistake, I suppose?” he sneered. “It would not surprise me,” replied Poirot, with a soupçon of malice. Giraud’s face took on a deeper tinge of red. “_Eh bien___, come in here. You shall judge for yourself.” He flung open the door of the _salon___, and we passed in, leaving Jack Renauld in the care of the two other men. “Now, M. Poirot,” said Giraud laying his hat on the table, and speaking with the utmost sarcasm, “I will treat you to a little lecture on detective work. I will show you how we moderns work.” “_Bien!___” said Poirot, composing himself to listen. “I will show you how admirably the Old Guard can listen,” and he leaned back and closed his eyes, opening them for a moment to remark. “Do not fear that I shall sleep. I will attend most carefully.” “Of course,” began Giraud, “I soon saw through all that Chilian tomfoolery. Two men were in it—but they were not mysterious foreigners! All that was a blind.” “Very creditable so far, my dear Giraud,” murmured Poirot. “Especially after that clever trick of theirs with the match and cigarette end.” Giraud glared, but continued: “A man must have been connected with the case, in order to dig the grave. There is no man who actually benefits by the crime, but there was a man who thought he would benefit. I heard of Jack Renauld’s quarrel with his father, and of the threats that he had used. The motive was established. Now as to means. Jack Renauld was in Merlinville that night. He concealed the fact—which turned suspicion into certainty. Then we found a second victim—_stabbed with the same dagger___. We know when that dagger was stolen. Captain Hastings here can fix the time. Jack Renauld, arriving from Cherbourg, was the only person who could have taken it. I have accounted for all the other members of the household.” Poirot interrupted: “You are wrong. There is one other person who could have taken the dagger.” “You refer to M. Stonor? He arrived at the front door, in an automobile which had brought him straight from Calais. Ah, believe me, I have looked into everything. M. Jack Renauld arrived by train. An hour elapsed between his arrival, and the moment he presented himself at the house. Without doubt, he saw Captain Hastings and his companion leave the shed, slipped in himself and took the dagger, stabbed his accomplice in the shed—” “Who was already dead!” Giraud shrugged his shoulders. “Possibly he did not observe that. He may have judged him to be sleeping. Without doubt they had a rendezvous. In any case he knew this apparent second murder would greatly complicate the case. It did.” “But it could not deceive M. Giraud,” murmured Poirot.