the vestibule, looked into
the garden, and had seen, coming towards the pavilion, Mademoiselle
Stangerson--alone. He would never have dared to attack her at that hour,
if he had not found her alone. His mind was made up. He would be more at
ease alone with Mademoiselle Stangerson in the pavilion, than he would
have been in the middle of the night, with Daddy Jacques sleeping in
the attic. So he shut the vestibule window. That explains why neither
Monsieur Stangerson, nor the keeper, who were at some distance from the
pavilion, had heard the revolver shot.

"Then he went back to The Yellow Room. Mademoiselle Stangerson came in.
What passed must have taken place very quickly. Mademoiselle tried to
call for help; but the man had seized her by the throat. Her hand had
sought and grasped the revolver which she had been keeping in the
drawer of her night-table, since she had come to fear the threats of
her pursuer. The murderer was about to strike her on the head with the
mutton-bone--a terrible weapon in the hands of a Larsan or Ballmeyer;
but she fired in time, and the shot wounded the hand that held the
weapon. The bone fell to the floor covered with the blood of the
murderer, who staggered, clutched at the wall for support--imprinting on
it the red marks--and, fearing another bullet, fled.

"She saw him pass through the laboratory, and listened. He was long at
the window. At length he jumped from it. She flew to it and shut it. The
danger past, all her thoughts were of her father. Had he either seen
or heard? At any cost to herself she must keep this from him. Thus
when Monsieur Stangerson returned, he found the door of The Yellow Room
closed, and his daughter in the laboratory, bending over her desk, at
work!"

Turning towards Monsieur Darzac, Rouletabille cried: "You know the
truth! Tell us, then, if that is not how things happened."

"I don't know anything about it," replied Monsieur Darzac.

"I admire you for your silence," said Rouletabille, "but if
Mademoiselle Stangerson knew of your danger, she would release you from
your oath. She would beg of you to tell all she has confided to you. She
would be here to defend you!"

Monsieur Darzac made no movement, nor uttered a word. He looked at
Rouletabille sadly.

"However," said the young reporter, "since Mademoiselle is not here, I
must do it myself. But, believe me, Monsieur Darzac, the only means to
save Mademoiselle Stangerson and restore her to her reason, i