“How can we return it?” Holmes muttered. “Quick, quick, we must think of some way! Where is the despatch-box?”

“Still in his bedroom.”

“What a stroke of luck! Quick, madam, bring it here!” A moment later she had appeared with a red flat box in her hand.

“How did you open it before? You have a duplicate key? Yes, of course you have. Open it!”

From out of her bosom Lady Hilda had drawn a small key. The box flew open. It was stuffed with papers. Holmes thrust the blue envelope deep down into the heart of them, between the leaves of some other document. The box was shut, locked, and returned to the bedroom.

“Now we are ready for him,” said Holmes. “We have still ten minutes. I am going far to screen you, Lady Hilda. In return you will spend the time in telling me frankly the real meaning of this extraordinary affair.”