ould be incontestible: the book published
under Louis XIV. Now of those hundred copies printed by the person who
was presumed to be the Man with the Iron Mask only two escaped the
flames. One was purloined by the captain of the guards and lost. The
other was kept by Louis XIV., handed down to Louis XV., and burnt by
Louis XVI. But a copy of the essential page, the page containing the
solution of the problem, or at least a cryptographic solution, was
conveyed to Marie Antoinette, who slipped it into the binding of her
book of hours. What has become of this paper? Is it the one which
Beautrelet has held in his hands and which Lupin recovered from him
through Bredoux, the magistrate's clerk? Or is it still in Marie
Antoinette's book of hours? And the question resolves itself into this:
what has become of the Queen's book of hours?

* * * * *

After taking a short rest, Beautrelet consulted his friend's father, an
old and experienced collector, who was often called upon officially to
give an expert opinion and who had quite lately been invited to advise
the director of one of our museums on the drawing up of the catalogue.

"Marie Antoinette's book of hours?" he exclaimed. "Why, the Queen left
it to her waiting-woman, with secret instructions to forward it to
Count Fersen. After being piously preserved in the count's family, it
has been, for the last five years, in a glass case--"

"A glass case?"

"In the Musee Carnavalet, quite simply."

"When will the museum be open?"

"At twenty minutes from now, as it is every morning."

* * * * *

Isidore and his friend jumped out of a cab at the moment when the doors
of Madame de Sevigne's old mansion were opening.

"Hullo! M. Beautrelet!"

A dozen voices greeted his arrival. To his great surprise, he
recognized the whole crowd of reporters who were following up "the
mystery of the Hollow Needle." And one of them exclaimed:

"Funny, isn't it, that we should all have had the same idea? Take care,
Arsene Lupin may be among us!"

They entered the museum together. The director was at once informed,
placed himself entirely at their disposal, took them to the glass case
and skewed them a poor little volume, devoid of all ornament, which
certainly had nothing royal about it. Nevertheless, they were overcome
by a certain emotion at the sight of this object which the Queen had
touched in those tragic days, which h