“Let us presume, for argument’s sake, that the document was taken by the maid or by the valet⁠—”

“They are both old and tried servants.”

“I understand you to say that your room is on the second floor, that there is no entrance from without, and that from within no one could go up unobserved. It must, then, be somebody in the house who has taken it. To whom would the thief take it? To one of several international spies and secret agents, whose names are tolerably familiar to me. There are three who may be said to be the heads of their profession. I will begin my research by going round and finding if each of them is at his post. If one is missing⁠—especially if he has disappeared since last night⁠—we will have some indication as to where the document has gone.”

“Why should he be missing?” asked the European Secretary. “He would take the letter to an Embassy in London, as likely as not.”

“I fancy not. These agents work independently, and their relations with the Embassies are often strained.”