ned quietly in her
seat, pretending to read her book, but all the while watching, with
anxious eyes, the door on the other side of the hall.

Richard Duvall, meanwhile, had entered the waiting room, his mind fully
made up as to the course he was about to pursue. During the few moments
which intervened, until the doctor's arrival, he looked keenly about the
room, examining it in detail, fixing its entrances and exits firmly in
his mind, so as to be prepared for any emergency which might arise.

The room was a large one. Along the side facing the entrance door, as
well as that which fronted on the park, were big curtained windows, set
in deep recesses, and between them, cases of books. At the far end of
the room, toward the rear of the house, was another door. Duvall stole
over to it, listened carefully, then slowly opened it and looked within.
The room proved to be the doctor's private office, and he saw at once
that it was built in a sort of ell, and could not be entered except
through the room in which he stood. There was a door, it is true, in the
right-hand wall, which had once given entrance to the hall, but against
this a heavy instrument case, with glass doors, now stood.

Duvall withdrew his head and shoulders from the doorway, nodding to
himself in a satisfied way, then noiselessly closed the door and
returned to the center of the room.

In a moment Dr. Hartmann came in, glancing at him sharply.
"Good-morning, sir," he remarked, in French. "You wish to see me?"

The detective took a card-case from his pocket and tendered the doctor a
card. It was one of many which he carried for such emergencies, and bore
the name of Stephen Brooks.

"Yes," he said, pleasantly. "I came to consult you concerning a curious
case."

"Indeed!" The doctor looked at the card carelessly. "I see that you are
an American." He began to speak in English. "Sit down, please."

"Thank you." Duvall took a chair.

"What is the nature of the case, may I ask?"

"Doctor--I've heard so much of your wonderful cures--of your remarkable
success in treating mental disorders, that I have ventured to come to
you in the hope that you may be able to help me."

The doctor smiled, not displeased at the other's flattery. "What is the
cause of your trouble, Mr. Brooks?"

Duvall observed him thoughtfully for a moment. "If a person has
delusions upon one particular subject, is he on that account necessarily
insane?"

"Not at all. Manias of various