"That's because your eyes aren't trained," replied the detective. "Look at that corner sofa, topped by that richly carved bracket. Observe the thick appearance of the delicate mahogany panel. You may be quite sure that it hides a solid steel casket which the best tools would have no easy job to cut through. That little moulding you see to the right can be easily pushed aside." Here Juve, with the precision of an expert, set the woodwork in motion and showed the astonished Fandor a scarcely visible key-hole. "Now, let's put out the light and hide ourselves behind the curtains. Luckily they are far enough from the window for our presence not to be noticed." For about an hour the men remained motionless, then, weary of standing, they squatted on the floor. Each had his revolver ready to hand. Ten had just struck from a distant clock when suddenly a slight sound reached their attentive ears. The two had whiled away the time of waiting by drilling the curtains with a small penknife. These holes were invisible at a distance, but enabled them to see what was going on in the room. The noise continued, slow and measured; some one was walking about in the adjacent rooms without any attempt to disguise the sound. Evidently Loupart believed himself quite alone in the house of the absent doctor. The steps drew nearer, and Fandor, in spite of his courage, felt the rapid beating of his heart. The handle of the door leading from the hall to the study was turned, and some person entered the room. There was an instant of silence, and then the desk was suddenly lit up. The new-comer had found the switch. But he was not Loupart. He seemed a man of forty and wore a brown beard, brushed fan-shape; a noticeable baldness heightened his forehead. On his strongly arched nose a double eye-glass was balanced. Suddenly, having looked at the clock which marked half-past eleven, he began to loosen his tie and unbutton his waistcoat and then went out, leaving the study lit as if intending to come back. "It's Chaleck!" exclaimed Fandor. "Just so," replied the detective. "And this complicates matters; we may have to protect him as well as his safe." Indeed, Juve's first impulse was to go straight to Doctor Chaleck, apprise him of the situation, and, under his guidance, search the house thoroughly. But that would have put Loupart on the alert. It would be taking too great a chance. If Juve should lay hands on him outside of Chaleck's house he would have no right to hold him. For the subtle power of Loupart, that well-loved hooligan of the purlieus of Paris, lay in his remaining constantly a source of fear, always a suspect without ever being caught with the goods. Coming back to his first idea of insuring Chaleck's safety, Juve said to himself: "The doctor is coming back here, that's sure, and we must protect him without his knowing it. That is the best plan for the present."