“No,” said Soames. “Understand me: Nothing may come of this. If a name gets out, or the watching is suspected, it may have very serious consequences.”

Mr. Polteed nodded. “I can put it into the cipher category. Under that system a name is never mentioned; we work by numbers.”

He unlocked another drawer and took out two slips of paper, wrote on them, and handed one to Soames.

“Keep that, sir; it’s your key. I retain this duplicate. The case we’ll call 7x. The party watched will be 17; the watcher 19; the Mansions 25; yourself⁠—I should say, your firm⁠—31; my firm 32, myself 2. In case you should have to mention your client in writing I have called him 43; any person we suspect will be 47; a second person 51. Any special hint or instruction while we’re about it?”

“No,” said Soames; “that is⁠—every consideration compatible.”