, Amy," she urged, "but you must hurry."

"Thank you for everything you have done to help me," the girl murmured
gratefully, moving to the window which Penny had opened for her. "I'll
never forget it."

"I've done nothing," Penny replied, assisting her to climb over the
sill. "Can you manage both bags?"

"Yes, I think so."

"Will you let me know the address of your new rooming house, Amy?"

"Yes, of course. I have no idea now where I'll go. I may not escape
at all."

"Keep to the alley," Penny advised. "Good-bye and good luck."

She stood watching from the window while Amy descended the fire escape
to enter the alley. The girl waved her hand reassuringly and vanished.

Penny closed the window and straightened up the room so that there
would be no appearance of sudden flight. She wondered if she had done
right to help Amy escape the police.

She felt troubled because the girl had failed to explain why she had
written to Mr. Hoges. Yet the letter provided Penny with a valuable
clue.

"Undoubtedly, the man told Amy to address him in care of General
Delivery," she thought. "That means he'll call there for his mail. If
I keep watch I may locate him."

Since the day Penny had encountered the museum workman at the Gage
Galleries, she had held to the theory that the man had something to do
with the mysterious disappearance of the priceless Rembrandt. It had
been her firm belief that if she apprehended Mr. Hoges for questioning,
the establishment of his own guilt would result in Amy's exoneration.
But now that she had learned the two were friends, she did not know
what to think. Certainly Amy's association with the man did not tend
to point to her own innocence.

"I'll not help the girl again unless she reveals everything concerning
her connection with Hoges," Penny decided. "From now on matters must
take their own course."

Leaving the bedroom, she went downstairs and out the front door. The
watchful detective was still stationed across the street, but Penny was
so engrossed in her own thoughts that she cast only a casual glance in
his direction.

She had walked a short distance down the street, when she felt a firm
pressure on her arm.

"Just a minute, young lady!"

Penny whirled around to find herself face to face with the police
detective.

CHAPTER XVI

Watchful Waiting

"What do you want?" Penny gasped. She felt certain the man intended to
arrest her for aiding Amy Coulter to