eves?"

"Something like that. We've set a trap."

"A trap?" Penny was all interest.

"Yes, we've planted several expensive new cars in key positions on the
street. Our men are secretly watching them, of course. We hope that
the auto thieves will select one of our models to strip."

"It must be tedious waiting."

"It is, but if we catch the gang our patience will have been rewarded."

"But what of Rap Molberg?" Penny questioned doubtfully. "Surely he
must delegate the actual thievery to others."

"I'm not so sure," Mr. Nichols said slowly. "It wouldn't surprise me
to learn that Molberg acts upon orders from someone higher up. However
that may be, if we capture some of the lesser fry, they can be made to
talk."

The detective busied himself at his desk. For a time Penny amused
herself by watching pedestrians through the field glass. Growing tired
of that, she buried herself in a magazine. It was not very
interesting. By nine o'clock she was thoroughly bored.

"I think I'll go home," she announced. "I don't believe anything
exciting will happen tonight."

"So that's why you came," her father chided. "And I thought it was
because you craved my company!"

"I did, but this bare office is too depressing."

"Then I'll excuse you," Mr. Nichols smiled. "Take a taxi home if you
like."

"No, I think I'll walk."

It was a pleasant mellow evening and Penny was in the mood for a long
stroll. She chose a roundabout route home.

She was absent-mindedly crossing a street, thinking of nothing in
particular, when an automobile without headlights shot past her at a
high rate of speed. Frightened, Penny sprang backwards.

"The nerve of that driver!" she thought. "He missed me by inches."

She watched the car swerve around a corner and race up a dead-end
street.

"Why, this is the very place where I lost track of Rap Molberg!" she
told herself.

She rushed to the corner. Her fascinated gaze followed the retreating
automobile. It tore madly to the end of the street where it abruptly
halted.

Penny lost sight of it for an instant. Then to her surprise, the
headlights were flashed on. In the reflected light she saw the tall
walls of a large manufacturing plant.

The beam was turned off again. Darkness swallowed up the car.

While she was straining to see, Penny heard the shrill blast of a
warning siren from far up the street. The next instant, a police radio
cruiser shot past.

With a loud sc