The voice of the American instantly broke the silence in a high,
nervous accent.

"And yet Sherlock Holmes himself," he cried, "could not decipher the
mystery which to-night baffles the police of London."

At these unexpected words, which carried in them something of the tone
of a challenge, the gentlemen about the table started as suddenly as
though the American had fired a pistol in the air, and Sir Andrew
halted abruptly and stood observing him with grave surprise.

The gentleman with the black pearl was the first to recover.

"Yes, yes," he said eagerly, throwing himself across the table. "A
mystery that baffles the police of London.

"I have heard nothing of it. Tell us at once, pray do--tell us at
once."

The American flushed uncomfortably, and picked uneasily at the
tablecloth.

"No one but the police has heard of it," he murmured, "and they only
through me. It is a remarkable crime, to, which, unfortunately, I am
the only person who can bear witness. Because I am the only witness, I
am, in spite of my immunity as a diplomat, detained in London by the
authorities of Scotland Yard. My name," he said, inclining his head
politely, "is Sears, Lieutenant Ripley Sears of the United States
Navy, at present Naval Attache to the Court of Russia. Had I not been
detained to-day by the police I would have started this morning for