But now that the pair are on the alert I cannot see
that anything can be gained by remaining in Madrid longer," I pointed
out.

"Then you intend to give up the quest for the truth?"

"Not by any means," I replied quickly. "I intend, at all hazards, and
at all costs, to still fathom the mystery. What we have learned since
we came to Spain puts quite a different complexion upon matters. We
are now in possession of certain facts concerning De Gex--facts of
which we had no suspicion. We had never dreamed that to further his
ends he did not hesitate to employ a notorious criminal to commit
murder with malice aforethought. Neither did we know anything of his
financial dealings with the Spanish Ministry of Finance, or his
partnership with the Conde de Chamartin, or that the drug he used
upon poor Gabrielle and myself was the obscure but most deadly and
dangerous orosin. All these are points which may in the near future be
of greatest advantage to us. Therefore we must not despair. Let us
take courage and continue to probe the mystery--for the sake of poor
Gabrielle Tennison," I urged. "Let us act as quietly and discreetly as
our enemy is acting, and we may yet attain success!"

CHAPTER THE NINETEENTH

THE TRACK OF DESPUJOL

Having decided to still remain in Madrid I deemed it advisable to
engage the services of a private inquiry agent to watch the movements
of De Gex and Suzor, who still remained at the Ritz. The mystery-man,
living under an assumed name, never went out in the daytime, though
Suzor often went forth, paying visits to certain banks and commercial
offices in connexion with the proposed new railway.

The man we engaged was an elderly ex-detective of the Seville police,
named Pardo, who very soon discovered the identity of the secret agent
employed to keep surveillance upon De Gex on behalf of the police so
that no harm should befall him.

In consequence, I took Pardo into my confidence, and calling him to my
hotel, explained that I desired to keep secret watch upon the
Frenchman Suzor, without the knowledge of the detective watching De
Gex.

"I particularly desire to know the addresses of any telegram which
Suzor may send. Probably he may send some message to Italy. If so,
please discover the address and the text of the message."

I believed that De Gex might communicate with Moroni, now that the
plot of Despujol had failed.

"I will watch, senor," was the grey-haired Spaniard's reply. "If Se