reaming of brakes, the police car came to a stop not far
from Penny.

"Did you see an automobile without headlights come this way?" the
driver asked tersely.

Penny was only too glad to offer information.

"It turned into this dead-end," she began.

The officers did not wait to hear more. With a roar, the cruiser was
off again. It reached the end of the street and halted because it
could go no farther.

Penny, bent upon missing nothing, followed as fast as she could.

By the time she reached the radio cruiser one of the officers had
alighted. He was looking carefully about. Sighting Penny, he walked
over to her.

"Say you! I thought you told us that car came this way."

"It did," Penny maintained staunchly. "I saw it go to the very end of
this street. The lights flashed on for an instant. Then the car
seemed to vanish. I think it must have gone into that building."

She indicated the Hamilton Manufacturing Plant. The officer surveyed
it briefly.

"Don't kid me!" he snapped. "Only a Houdini ever went through solid
walls!"

He climbed back into the police car, saying gruffly to the driver: "Get
going, Philips. It was a wrong steer. We must have missed that car at
the turn."

Penny waited until the cruiser disappeared around the corner. Then she
crossed the street and stood staring meditatively at the tall walls of
the Hamilton Plant. There was no doorway leading into the building.

"It's uncanny," she murmured. "Yet I know very well that car went in
there some way." The building was entirely dark. There were no
windows on the street side. Only a vast expanse of unbroken wall.

"It's too dark to see anything tonight," Penny decided after a brief
hesitation. "Tomorrow I'll come back and perhaps make a few
interesting discoveries!"

And with that resolution, she turned and walked rapidly toward home.

CHAPTER X

The Vanishing Car

Penny fully intended to tell her father of her experience, but she
retired before he came home. She overslept the next morning. When she
descended to the breakfast room at nine o'clock, Mrs. Gallup told her
that the detective had been gone for nearly an hour.

"Your father wasn't in a very good mood this morning," the housekeeper
informed as she served Penny with a steaming hot waffle. "He
complained about the coffee. When he does that it's always because
something's gone wrong with his work."

"You mustn't mind Dad," Penny smiled. "We could