“No,” my friend said. “Forgive me, Ralph, for speaking quite plainly, but in this affair we are both working towards the same end—namely, to elucidate the mystery. We cannot hope for success if you are bent upon concealing your discoveries from me.”
“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.