"and if his accomplices are sure of it,
then see to the safety of Mlle. de Saint-Veran. Monsieur le Juge
d'Instruction, for the vengeance will be terrible."

* * * * *

A few minutes later and in spite of the entreaties of M. Filleul, who
would gladly have made further use of this fascinating auxiliary,
Isidore Beautrelet, whose holidays ended that day, went off by the
Dieppe Road. He stepped from the train in Paris at five o'clock and, at
eight o'clock, returned to the Lycee Janson together with his
schoolfellows.

Ganimard, after a minute, but utterly useless exploration of the ruins
of Ambrumesy, returned to Paris by the fast night-train. On reaching
his apartment in the Rue Pergolese, he found an express letter awaiting
him:

* * * * *

Monsieur l'Inspecteur Principal:

Finding that I had a little time to spare at the end of the day, I have
succeeded in collecting a few additional particulars which are sure to
interest you.

Arsene Lupin has been living in Paris for twelve months under the name
of Etienne de Vaudreix. It is a name which you will often come across
in the society notes or the sporting columns of the newspapers. He is a
great traveler and is absent for long periods, during which, by his own
account, he goes hunting tigers in Bengal or blue foxes in Siberia. He
is supposed to be in business of some kind, although nobody is able to
say for certain what his business is.

His present address is 38, Rue Marbeuf; and I will call your attention
to the fact that the Rue Marbeuf is close to Post-office Number 45.
Since Thursday the twenty-third of April, the day before the burglary
at Ambrumesy, there has been no news at all of Etienne de Vaudreix.

With very many thanks for the kindness which you have shown me, believe
me to be,
Monsieur l'Inspecteur Principal,
Yours sincerely,
ISIDORE BEAUTRELET.

P.S.--Please on no account think that it cost me any great trouble to
obtain this information. On the very morning of the crime, while M.
Filleul was pursuing his examination before a few privileged persons, I
had the fortunate inspiration to glance at the runaway's cap, before
the sham flyman came to change it. The hatter's name was enough, as you
may imagine, to enable me to find the clue that led to the
identification of the purchaser and his address.

* * * * *

The next morning,