ould hear voices but
this time it was impossible to catch even a word.

Penny moved on to the next door. She gently turned the knob. The door
was locked. So were all the others along the corridor until she came
to the last one.

To Penny's surprise, it opened. Cautiously, she peeped inside. The
room appeared to be empty. She entered.

It was only a small office, empty of furniture. A few papers were
scattered over the bare floor, but upon examination Penny found them of
no significance. It was clear that if she were to learn anything of
value, she must find a means of entering the room where Hanley Cron,
the ex-museum worker and the others were talking.

An inside door opened into an adjoining room. Penny was elated to find
it unlocked. But her satisfaction was of short duration, for the next
office likewise was empty and devoid of any clues.

By placing her ear against the north wall, she was able to hear the
three men talking. It was provoking to be so close and yet unable to
learn what they were saying. She felt convinced that if only she could
hear their conversation, a great many puzzling matters might be cleared
up.

Presently, Penny heard a door slam. She peeped out into the hallway in
time to see Cron, Hoges and another man disappearing down the stairway.

"The coast is clear now!" she thought. "If I can just find some way to
enter that room while they're away!"

She made another tour of the hall, trying the door. As she had
anticipated it was locked.

Returning to the room she had just left, she went to the window and
looked out. A wide ledge of stone extended along the wall of the
building, connecting the windows. At best it offered a dangerous
footing. Yet Penny was tempted to try to reach the adjoining room by
means of it, for there was no other way to gain admittance.

She raised the window and looked down. Her courage nearly failed her.
While the ledge was wide, it meant a long fall and instant death should
she become dizzy and lose her balance.

"I can do it--easy," Penny told herself grimly.

Climbing out on the ledge, she clutched an overhanging telephone wire
for support and cautiously eased herself along, an inch at a time. She
kept her gaze ahead, resisting the temptation to glance toward the
deserted street.

She reached the next window which was open an inch at the bottom. The
gap provided a finger-hold and enabled her to raise the window. With a
sigh of inten