er's place."

The young man shifted his weight uneasily. "Oh, by the way," he said,
"I don't suppose you found a package of letters in the rumble seat?"

"Letters?" repeated Penny.

"I thought perhaps they might have dropped from my pocket while I was
riding with you."

"Were they valuable?" asked Penny very innocently.

"Only to me," answered Walter Crocker shortly. "But I must have them
back. Do you mind if I look in the back end of your car?"

"You'd be welcome to search if it were here."

"Where is the car?" demanded the man, in his anxiety forgetting to be
polite.

"I couldn't say right now, Mr. Crocker. My father has the automobile."

"When will he return?"

"Probably not before evening," Penny replied, thinking quickly. "You
might drop back after supper. He should be here by then."

"Thank you," said Walter Crocker shortly.

He climbed into the car and drove away.

"That's a good one!" laughed Penny, highly amused. "He has lost the
Crocker letters all right, and he thinks they may be in our car!"

"Don't you expect your father home before night?" asked Susan.

"Of course I don't know exactly when he'll come," chuckled Penny. "But
I'd not be surprised to see him driving in any minute. I wanted to
give myself plenty of time to examine the car before Mr. Crocker
returns."

"What would you do if you found the letters, Penny?"

"I haven't thought that far," Penny admitted. "But the chance that
they're in our car is a very slim one."

The girls stationed themselves on the front porch so that they would
not miss Mr. Nichols when he drove in. Two hours later they glimpsed
the car coming up Knob Hill.

Penny meant to tell her father everything that had happened during the
day, but the detective seemed to have important matters on his mind.
When the girls ran down to the car to meet him, he responded
absent-mindedly to their greetings and went on into the cottage.

"Penny!" exclaimed Susan. "There's another auto coming up the hill!"

"And it looks like Walter Crocker's car!" Penny cried in alarm.
"Quick! We've no time to lose!"

The girls darted to Mr. Nichols' automobile and lifted up the rumble
seat. While Susan anxiously watched the road, Penny climbed up and
peered into the bottom of the car.

"Susan, they're here!" she squealed in delight.

"And so is Walter Crocker," Susan muttered in an undertone. "He's
looking right this way."

With her back turned to the approaching a