we were playing tennis yesterday."

"How could I when I didn't know anything about it myself until an hour
ago? That's the way Dad does things, Susan."

"I suppose you're going off on another one of those exciting mystery
cases," Susan said enviously.

"I only wish we were," sighed Penny. "This vacation won't be a bit
exciting. Dad just wants a complete rest at a quiet place. He says
he'll not even think about work while we're gone."

"What sort of place is Knob Hill?"

"From all I can learn it's just a dead spot on the map," Penny
declared. "And we've rented a cottage sight unseen."

"Oh, it may not be half bad," said Susan encouragingly. "You'll
probably be able to do a lot of interesting things--swim, hike or ride."

"Not at Knob Hill," replied Penny, shaking her head. "It isn't a
summer resort place at all. There will be absolutely nothing to do
except eat, sleep, and grow fat."

Susan laughed as she glanced at her chum's slender figure. Penny was
too active and athletic ever to be plump. She had sparkling blue eyes,
golden hair, and a natural smile. It was very easy for her to make
friends.

"I haven't finished my packing yet," said Penny. "I'll have to get
back home or I'll keep Dad waiting."

"I'm terribly sorry to see you go," Susan told her. "Don't forget to
send me a postcard now and then."

Penny promised that she would write often, and then, aware that time
was slipping away, said a hurried farewell. Reaching her own home, a
large white house on Hilburn Street, she found her father washing the
car in the back yard.

Christopher Nichols was a tall, slim man with graying hair. For many
years he had been in charge of the Nichols Detective Agency and was
well known not only in Belton City but throughout the state. Many
persons believed that Penny had inherited her father's sleuthing
ability, for even at the age of fifteen she had shown remarkable talent
in solving mystery cases.

As Penny paused for a moment to chat with her father before going into
the house, she noticed the tired lines of his face.

"Dad really needs a long rest," she thought. "I ought to be glad we're
both running off to a quiet place like Knob Hill."

"Hello, Penny," Mr. Nichols greeted his daughter. "I'll have this
cleaning job done in another ten minutes. Then I'm ready to start
whenever you are."

"You seem anxious to get away from Belton City," Penny smiled. "You're
not trying to escape from any c