door when he went out.

Without any clear idea of what he intended to do, Duvall went to the
door and tried it. To his surprise, he found it unlocked, and in a
moment he had passed out into the hall.

The house seemed deserted. Even the attendant who had sat at the head of
the stairs the night before was no longer in evidence. He went down to
the lower floor without seeing any one. As he passed the door of the
doctor's office, on his way to the entrance, he heard it open, and Dr.
Hartmann looked out at him with a grim smile. "Ah--going for a stroll, I
see, Mr. Duvall," he said, pleasantly enough. "It's a fine morning. I
hope you enjoy it."

Duvall made no reply. He appreciated fully that Hartmann was only making
fun of him, and realized his helplessness.

Once outside the door, he paused for a moment to drink in the beauty of
the morning. Straight ahead of him stretched the driveway which led to
the main road. The ornamental iron gate stood invitingly open. He went
toward it, unconsciously pondering upon his situation and what he could
do, if anything, to escape from it. At the gate he paused, looking about
carefully to see whether his movements were observed. There appeared to
be no one near him, although along one of the paths to the right of the
house, he saw several persons walking, whom he judged to be inmates of
the place. One or two others sat on benches among the shrubbery,
reading. None of them seemed to take the least interest in his
movements.

An empty cab passed slowly, the driver on the lookout for a fare. For a
moment the detective thought of escape, his hand came up with a jerk to
signal the cabman, then suddenly he let it fall with an exclamation of
dismay. He could not escape--he did not dare attempt it, knowing that
the snuff box, which had already caused him so much anxiety and trouble,
lay in a corner of the room beneath the doctor's laboratory. First he
must get that, before he could attempt to escape. He turned slowly back
toward the house.

Then suddenly another doubt assailed him. Had not Dr. Hartmann allowed
him this liberty merely to see whether or not he would take advantage of
it? Would the latter conclude, now that he had failed to do so, that the
snuff box was hidden somewhere on the premises? The thought disturbed
him greatly.

Still another consideration occurred to him. If he made any attempt to
recover the box, would his doing so not show his captors at once that
they had over