lf that with the
key in the lock, the door could not possibly be opened from without with
another key. Having made sure of all these details, he let fall these
words: "That's better!"--Then sitting down on the ground, he hastily
took off his boots and, in his socks, went into the room.

The first thing he did was to examine minutely the overturned furniture.
We watched him in silence.

"Young fellow, you are giving yourself a great deal of trouble," said
Daddy Jacques ironically.

Rouletabille raised his head and said:

"You have spoken the simple truth, Daddy Jacques; your mistress did not
have her hair in bands that evening. I was a donkey to have believed she
did."

Then, with the suppleness of a serpent, he slipped under the bed.
Presently we heard him ask:

"At what time, Monsieur Jacques, did Monsieur and Mademoiselle
Stangerson arrive at the laboratory?"

"At six o'clock."

The voice of Rouletabille continued:

"Yes,--he's been under here,--that's certain; in fact, there was no
where else where he could have hidden himself. Here, too, are the marks
of his hobnails. When you entered--all four of you--did you look under
the bed?"

"At once,--we drew it right out of its place--"

"And between the mattresses?"

"There was only one on the bed, and on that Mademoiselle was placed; and
Monsieur Stangerson and the concierge immediately carried it into the
laboratory. Under the mattress there was nothing but the metal netting,
which could not conceal anything or anybody. Remember, monsieur, that
there were four of us and we couldn't fail to see everything--the
chamber is so small and scantily furnished, and all was locked behind in
the pavilion."

I ventured on a hypothesis:

"Perhaps he got away with the mattress--in the mattress!--Anything
is possible, in the face of such a mystery! In their distress of mind
Monsieur Stangerson and the concierge may not have noticed they were
bearing a double weight; especially if the concierge were an accomplice!
I throw out this hypothesis for what it is worth, but it explains many
things,--and particularly the fact that neither the laboratory nor the
vestibule bear any traces of the footmarks found in the room. If,
in carrying Mademoiselle on the mattress from the laboratory of the
chateau, they rested for a moment, there might have been an opportunity
for the man in it to escape.

"And then?" asked Rouletabille, deliberately laughing under the bed.

I felt rat