Something in the silence which greeted his words made him look up. There was a puzzled look upon his companion’s face. “I opened the door with my own key,” said the younger man slowly. “You opened----” The man called George frowned. “I do not understand you, Callidino. I left the door open, and you walked in after me; I went straight up the stairs, and you followed.” Callidino looked at the other and shook his head. “I opened the door myself with the key,” he said quietly. “If anybody came in after you--why, it is up to us, George, to see who it is.” “You mean----?” “I mean,” said the little Italian, “that it would be extremely awkward if there is a third gentleman present on this inconvenient occasion.” “It would, indeed,” said the other. “Why?” Both men turned with a start, for the voice that asked the question without any trace of emotion was the voice of a third man, and he stood in the doorway screened from all possibility of observation from the window by the angle of the room. He was dressed in an evening suit, and he carried a light overcoat across his arm. What manner of man he was, and how he looked, they had no means of judging, for from his chin to his forehead his face was covered by a black mask. “Please do not move,” he said, “and do not regard the revolver I am holding in the light of a menace. I merely carry it for self-defence, and you will admit that under the circumstances, and knowing the extreme delicacy of my position, I am fairly well justified in taking this precaution.” George Wallis laughed a little under his breath. “Sir,” he said, without shifting his position, “you may be a man after my own heart, but I shall know better when you have told me exactly what you want.” “I want to learn,” said the stranger. He stood there regarding the pair with obvious interest. The eyes which shone through the holes of the mask were alive and keen. “Go on with your work, please,” he said. “I should hate to interrupt you.” George Wallis picked up the blow-pipe and addressed himself again to the safe door. He was a most adaptable man, and the situation in which he found himself nonplussed had yet to occur. “Since,” he said, “it makes absolutely no difference as to whether I leave off or whether I go on, if you are a representative of law and order, I may as well go on, because if you are not a representative of those two admirable, excellent and necessary qualities I might at least save half the swag with you.” “You may save the lot,” said the man sharply. “I do not wish to share the proceeds of your robbery, but I want to know how you do it--that is all.” “You shall learn,” said George Wallis, that most notorious of burglars, “and at the hands of an expert, I beg you to believe.” “That I know,” said the other calmly.