“I must confess,” he said with a smile, “that I did not suspect you of having so complete a knowledge of my doings or of my many secrets. I remembered my folly at eleven o’clock that night, and came back for what I had left behind. I found them exactly where I had left them, but somebody else had found them, too, and that somebody else had taken a wax impression of them. Moreover,” he leant forward towards Gilbert, lowering his voice, “that somebody else has since formed the habit of coming to this place nightly for reasons of his own. Do you know what those reasons are, Mr. Standerton?” “To choose a safe?” suggested Gilbert ironically. “He comes to rob us of the fruits of our labour,” said Wallis. He smiled as he said the words because he had a sense of humour. “Some individual who has a conscience or a sense of rectitude which prevents him from becoming an official burglar is engaged in the fascinating pursuit of robbing the robber. In other words, some twenty thousand pounds in solid cash has been taken from my safe.” “Borrowed, I do not doubt,” said Gilbert Standerton, and leant back in his chair, his hands stuffed into his pockets, and a hard look upon his face. “What do you mean--borrowed?” asked Wallis in surprise. “Borrowed by somebody who is desperately in need of money; somebody who understands the Stock Exchange much better than many of the men who make a special study of it; somebody with such knowledge as would enable him to gamble heavily with a minimum chance of loss, and yet, despite this, fearing to injure some unfortunate broker by the accident of failure.” He leant towards Wallis, his elbow upon the desk, his face half averted from the other. He had heard the outer door close with a bang, and knew they were alone now, and that Wallis had designed it so. “I wanted money badly,” he said. “I could have stolen it easily. I intended stealing it. I watched you for a month. I have watched criminals for years. I know as many tricks of the trade as you. Remember that I was in the Foreign Office, in that department which had to do mainly with foreign crooks, and that I was virtually a police officer, though I had none of the authority.” “I know all about that,” said Wallis. He was curious, he desired information for his own immediate use, he desired it, too, that his sum of knowledge concerning humanity should be enlarged. “I am a thief--in effect. The reason does not concern you.” “Had the ‘Melody in F’ anything to do with it?” asked the other dryly. Gilbert Standerton sprang to his feet. “What do you mean?” he asked. “Just what I say,” said the other, watching him keenly. “I understand that you had an eccentric desire to hear that melody played. Why? I must confess I am curious.” “Reserve your curiosity for something which concerns you,” said the other roughly. “Where did you learn?” he added the question, and Wallis laughed. “We have sources of information----” he began magniloquently.