During the time he had been in the cab he had been thinking of the means he should use to clear himself, for he felt sure he could do so. Sitting alone in the cell, however, this became impossible. Such a terror as he had never known before filled his heart. He believed he knew who had committed this ghastly deed, but his lips must be sealed. He must not tell; he would rather die than tell of what he knew. His mother, out of love for him, and with a desire to be revenged upon the man who had been his enemy, had, in her mad passion, taken away his life. He called to mind the incidents of the previous day. He remembered that, not long after he had arrived at his office that morning, his mother came to see him. She had come in by a side entrance and had found her way across a little piece of intervening yard, and had thus come to his office without the notice of others--at least, he hoped so; at any rate, it was quite possible that she should have done so. He wondered why she had come that morning, because she seemed to have nothing to say to him of importance. But while they were there, she had noticed a large knife lying upon his desk. It had been sent to him some time before by a man from South America, with whom he had done business. It was an ugly, murderous-looking weapon, and keen as a razor. He remembered her asking questions about it. Soon after he had been called out of the office, and when he returned he noticed that it was not lying on the table. He had paid no particular attention to this fact at the time, because his mind had been filled with other things. He had been trying to discover Ned Wilson's whereabouts, and he had been thinking of the things he meant to say to him. During the afternoon he had forgotten all about his mother--he had reason to--but on his return, after he had told her all that had taken place, he remembered she seemed like one bereft of her senses. Every detail of the interview they had together came to him there, as he sat alone in the darkness, thinking and remembering. He called to mind every word she had spoken; and, in the light of after events, he thought he could plainly see their meaning. She had told him that he need not fear, that he should be avenged, that the desires of his heart should be realised. She had said something about Howden Clough. He had paid no particular attention to it then, as he fancied she was thinking of the place where he had quarrelled with Wilson; but now he knew.