own a copy of a stolen painting. If this picture is a fake, the police
would have no case against Mrs. Dillon."

The problem was too deep for Penny. She decided to reveal to no one
the discovery she had made until after she had discussed the matter
with her father. Quickly, she arose and went to the door.

To her surprise it did not open when she turned the knob. It took an
instant for the truth to dawn upon her. The door was locked!

"Mrs. Dillon must have turned the key when she went out," Penny
thought, recalling that she had heard a slight metallic click. "Now I
am in it!"

She considered calling for help but immediately abandoned the idea. It
would be difficult to explain how she had been locked in the library
without revealing the true details. And Mrs. Dillon would instantly
suspect that she had seen the hidden painting.

The room had two windows looking out upon the front lawn. Directly
beneath was a cultivated bed of flowers which Penny decided must be
sacrificed if necessary to the occasion. She switched out the electric
lights, and raising one of the windows peered in both directions to see
that the coast was clear.

Quickly she climbed over the sill, hung by her fingers tips for an
instant, then dropped lightly down to the ground, crushing several
choice plants underfoot.

Before she could turn she felt her arms pinioned behind her back in a
grasp of steel.

"Not so fast, young lady!" said a gruff voice.

Penny whirled around to face the man who had captured her. She began
to laugh.

"Dad!"

"Penny! I thought I had caught a young lady burglar. What are you
trying to do?"

"Escape from the library."

"So I observe. But have you any objection to using a door? In polite
society I believe that's the accepted method of leaving a house."

"The library door was locked," Penny explained hastily. "And I have
good reason for wanting to get away without being seen by anyone."

"In that case, always close the window after you," Mr. Nichols
chuckled. "Here, I'll boost you up and you can pull it down."

After Penny had lowered the sash, they hurriedly moved away from the
window.

"Now tell me all about it," the detective invited. "Did you lose your
bag of loot?"

"You know very well I wasn't doing anything I shouldn't," Penny
countered, "but you nearly frightened me to death when you nabbed me."

"I just happened to see you climbing out of the window as I came up the
path," the