asionally, Mr. Nichols came
to her rescue with very acceptable gifts of tires and spare parts.

Reaching the tennis court, Penny parked her car on a near-by street.
She found Susan Altman, her chum, already awaiting her.

"It's almost too hot today for tennis," the dark-haired girl complained
as she took her position at the baseline of the cement court, preparing
to serve the first ball.

For two long hours the girls battled back and forth. Although usually
they were well matched, upon this particular day Susan found herself
unable to cope with her companion's sizzling service and well-placed
drives. Finally, after completely missing a ball which Penny had sent
over the net with bullet-like speed, she threw down her racquet in
disgust.

"I've had enough punishment! That makes the third straight set you've
won."

"It's getting almost too dark to see the ball," Penny said generously.
"Shall we call it an evening and finish off with something to eat?"

They crossed over to Eby's Cafe, a favorite haunt of Belton City's
younger set. The booths were quite deserted.

"Everyone seems to have gone away for the summer," Susan mourned as she
pondered over the menu. "I suppose you'll be leaving soon too, Penny."

"No chance of it, I'm afraid. Dad has become involved in a new case
which may keep us in town indefinitely."

"I wish my father were a detective," Susan commented a trifle
enviously. "It's too bad about the vacation of course, but your life
is exciting at least."

It seemed to her that Penny always led an unhampered, adventurous
existence. At any rate, the girl was well acquainted with interesting
happenings at the Belton City police court and had more than a nodding
acquaintance with fascinating personages of the city.

"I've never had any real adventures," Penny declared gloomily.
"Unfortunately, Dad is a little secretive about his sleuthing
activities. I'd give anything to know about this latest case----"

Her voice trailed off for the two girls had heard a shrill warning
whistle which they instantly recognized as the fire siren. Although
they had not even begun their suppers they rushed to the plateglass
window to watch the red engine clatter by.

"Why, it's turning down our street!" Susan exclaimed. "Oh, I hope our
house isn't afire!"

"Let's jump in my car and follow," Penny proposed.

They hurriedly left the cafe. Penny had parked her roadster just out
of sight around the corner. But