"This is a private affair of my own," I declared doggedly. "What I have found only concerns myself."
He shrugged his shoulders with an air of distinct dissatisfaction.
"Even if it is a purely private matter we are surely good friends enough to be cognisant of one another's secrets," he remarked.
"Of course," I replied dubiously. "But only up to a certain point."
"Then, in other words, you imply that you can't trust me?"
"I can trust you, Ambler," I answered calmly. "We are the best of friends, and I hope we shall always be so. Will you not forgive me for refusing to show you these letters?"
"I only ask you one question. Have they anything to do with the matter we are investigating?"
I hesitated. With his quick perception he saw that a lie was not ready upon my lips.
"They have. Your silence tells me so. In that case it is your duty to show me them," he said, quietly.
I protested again, but he overwhelmed my arguments. In common fairness to him I ought not, I knew, keep back the truth. And yet it was the greatest and most terrible blow that had ever fallen upon me. He saw that I was crushed and stammering, and he stood by me wondering.
"Forgive me, Ambler," I urged again. "When you have read this letter you will fully understand why I have endeavoured to conceal it from you; why, if you were not present here at this moment, I would burn them all and not leave a trace behind."
He took it eagerly, skimmed it through, and started just as I had started when he saw the signature. Upon his face was a blank expression, and he returned it to me without a word.
"My opinion is the same as your own, Ralph, old fellow," he answered slowly, looking me straight in the face. "It is amazing--startling--tragic."
"You think, then, that the motive of the crime was jealousy?"
"The letter makes it quite plain," he answered huskily. "Give me the others. Let me examine them. I know how severe this blow must be to you, old fellow," he added, sympathetically.
"Yes, it has staggered me," I stammered. "I'm utterly dumfounded by the unexpected revelation!" and I handed him the packet of correspondence, which he placed upon the table, and, seating himself, commenced eagerly to examine letter after letter.
While he was thus engaged I took up the first letter, and read it through--right to the bitter end.