“That can be done in a very few words, Mr. Holmes. The letter⁠—for it was a letter from a foreign potentate⁠—was received six days ago. It was of such importance that I have never left it in my safe, but have taken it across each evening to my house in Whitehall Terrace, and kept it in my bedroom in a locked despatch-box. It was there last night. Of that I am certain. I actually opened the box while I was dressing for dinner and saw the document inside. This morning it was gone. The despatch-box had stood beside the glass upon my dressing-table all night. I am a light sleeper, and so is my wife. We are both prepared to swear that no one could have entered the room during the night. And yet I repeat that the paper is gone.”

“What time did you dine?”

“Half-past seven.”

“How long was it before you went to bed?”

“My wife had gone to the theatre. I waited up for her. It was half-past eleven before we went to our room.”