“Now exactly what do you want?” asked Gilbert. “Will you have a cigar?” Mr. Wallis pushed the box towards him. Gilbert smiled. “You need not be scared of them,” said Wallis with a twinkle in his eye. “There is nothing dopey or wrong with these, they are my own special brand.” “I do not smoke cigars,” said Gilbert. “Lie number one,” replied Wallis cheerfully. “This is a promising beginning to an exchange of confidences. Now, Mr. Standerton, we are going to be very frank with one another, at least I am going to be very frank with you. I hope you will reciprocate, because I think I deserve something. You know so much about me, and I know so little about you, that it would be fair if we evened matters up.” “I take you,” said Gilbert, “and if I can see any advantage in doing so you may be sure I shall act on your suggestion.” “A few months ago,” said Mr. Wallis, puffing slowly at his cigar, and regarding the ceiling with an attentive eye, “I and one of my friends were engaged in a scientific work.” Gilbert nodded. “In the midst of that work we were interrupted by a gentleman, who for a reason best known to himself modestly hid his features behind a mask.” He shrugged his shoulders. “I deplore the melodrama, but I applaud the discretion. Since then,” he went on, “the efforts of my friends in their scientific pursuit of wealth have been hampered and hindered by that same gentleman. Sometimes we have seen him, and sometimes we have only discovered his presence after we have retired from the scene of our labour. Now, Mr. Standerton, this young man may have excellent reasons for all he is doing, but he is considerably jeopardising our safety.” “Who is the young man?” asked Gilbert Standerton. “The young man,” said Mr. Wallis, without taking his eyes from the ceiling, “is yourself.” “How do you know?” asked Gilbert quietly. “I know,” said the other with a smile, “and there is an end to it. I can prove it curiously enough without having actually spotted your face.” He pulled an inkpad from the end of the desk. “Will you make a little finger-mark upon that sheet of paper?” he asked, and offered a sheet of paper. Gilbert shook his head with a smile. “I see no reason why I should,” he said coolly. “Exactly. If you did we should find a very interesting finger-mark to compare with it. In the office here,” Mr. Wallis went on, “we have a large safe which has been on our hands for some months.” Gilbert nodded. “Owned by a client who has the keys,” he said. “Exactly,” said Wallis. “You remember my lie about it. There are three sets of keys to that safe and a combination word. I said three”--he corrected himself carefully--“there are really four. By an act of gross carelessness on my part, I left the keys of the safe in my pocket in this very office three weeks ago.