“Surely, sir, you knew that there was a detective in the house?”

“My dear Israel, I knew nothing of the kind.”

He thought for a moment, and then added: “I think I ought to have been told.”

“I thought you knew, sir.”

“Are you sure it was a detective?”

“Quite sure.”

But even as I spoke I remembered that I only had my own deductions to guide me. No one had told me he was a detective. I searched swiftly in my brain for some excuse, but could think of none.

“How did you know he was a detective?”

“I heard him questioning one of the servants.”

“Which servant?”