go he visited the house of
Mr. De Gex."

"Yes, he is his friend, just as Despujol was," I remarked.

"But I cannot understand that!" Rivero declared. "It seems incredible
that a person of such high standing as Mr. De Gex should number
bandits among his friends!"

"I revealed to you the truth concerning De Gex when we were in Nimes,"
I said. "Even then you were half inclined to disbelieve it. Now you
know the truth. The two business partners of Oswald De Gex, the Conde
de Chamartin, of Madrid, and the Baron van Veltrup, of Amsterdam, have
both died suddenly--and at the instigation of their unsuspected
friend! It has been proved that Sanz introduced the tiny scrap of
infected razor-blade into the Baron's glove."

"At De Gex's instigation?--impossible!"

"De Gex was the only person to profit by the Baron's death," I pointed
out. "He owed a large sum to the Baron over a financial deal, and by
the latter's death, and the destruction of certain papers, he now
escapes payment."

"But you surely do not allege that Mr. De Gex resorts to the use of
this little known and unsuspected poison in order to secure his own
ends!" cried the famous detective, as he sat opposite me in an
easy-chair.

"When we know the truth--as I hope we may very soon--then you will be
staggered," I assured him. "At present you do not know the whole of
the amazing story. For certain private reasons I have been unable to
reveal it to you. But slowly, piece by piece, I have been steadily
working upon the mystery of certain amazing occurrences at De Gex's
house in Stretton Street. By slow degrees, and after travelling up
and down Europe, I have at last succeeded in finding just a streak of
daylight through the impenetrable barrier so cleverly contrived in
order to mystify and mislead me. If you desire to ascertain the great
ramifications of the desperate plots conceived by De Gex and his
friends, and take steps to combat them, it will be best to allow his
accomplice Sanz further liberty. Keep vigilant watch, but do not allow
him to suspect," I urged. "He will no doubt go to Stretton Street
again. Sanz, though a hired assassin as was his friend Despujol,
should not be arrested yet, for the longer he remains at liberty the
more extensive will be our information against the arch-schemer of
Europe, Oswald De Gex."

Rivero spent the evening with me. We dined at the Clarendon, across
Hammersmith Bridge, and afterwards we idled in one of the foreign
cafes