At that time I never dreamed that the great financier who controlled
the destinies of certain European States never moved without a police
official being in attendance, and that surveillance was kept upon him
as though he were royalty travelling incognito. De Gex, it seemed, was
ever afraid that one of his enemies, the hundreds whom he had ruined
by dint of sharp practice, unscrupulous dealing, and flagrant bribery,
might seek revenge.

Hence, though neither Hambledon nor myself knew of it, both De Gex and
his toady and agent, Gaston Suzor, were well aware of our presence,
and, moreover, were kept posted concerning our movements from day to
day!

Though we were in ignorance of all this, yet the desperate nature of
the plot against me caused me to wonder what exactly was the fear in
which De Gex held me. Of course it concerned Gabrielle Tennison. But
exactly how, I failed to surmise.

One thing was certain, that the mystery-man of Europe intended to rid
himself of me, and in this he was being aided by certain of his
friends, chief among whom were Suzor and Moroni. That the assassin
Despujol was only a paid servant was quite clear. But the pay must
have been a very handsome sum to cause him to dare to come to Madrid
so boldly and run the risk of arrest.

I smiled at my own innocence when I remembered how completely he had
imposed upon me by showing me his papers of identity, and the
photographs of his pretended family. Truly only a great criminal could
have remained so imperturbed and polite to the man whom he intended
should die.

"This drug orosin is a very mysterious one, I suppose?" I remarked a
few seconds later as the Professor, who had offered me a cigar, was in
the act of lighting up.

"Yes. A very weak solution taken by the mouth produces extraordinary
effects upon the human brain. The latter almost instantly becomes
unbalanced and the victim lapses into an unconscious state for days,
even for weeks," he said. "Very often the brain is quite normal, save
that a complete loss of memory follows the return to consciousness. In
other cases orosin has produced complete and hopeless dementia."

"Always hopeless?" I asked eagerly, recollecting my own case and that
of Gabrielle Tennison.

"Not always hopeless. There have been cases that have been cured."

"Do you know any personally?" I demanded breathlessly.

"There are one or two--very few--on record. Professor Gourbeil, the
well-known alienist of Lyons,