now how it came to be on
the floor."

"It was there because you dropped it," the matron said sternly. "Next
time be more careful about accusing persons."

Penny and Susan turned to go to their own lockers, but before they
could leave, Betty came toward them timidly.

"Thank you so much," she said in a low tone. "I owe you a great deal."

"Not at all," Penny returned, a trifle stiffly.

"I feel ashamed of the way I have acted lately," the girl went on
hurriedly, avoiding Penny's penetrating gaze. "I've been so upset
about everything. I wish I could explain--but I can't."

"I think perhaps I understand."

Betty stared hard at Penny. But she quickly masked the fleeting
expression of alarm. After thanking her friends again, she turned and
disappeared in the direction of the hair drying room.

"Just what is it that upsets that girl so?" Penny said in an undertone
to Susan as they went to their own lockers. "She acts as if she's
afraid we'll discover something about her."

"Yes, she does. I can't figure it out at all."

The girls quickly dressed but by the time they had dried their hair and
were ready for the street, it was long past supper time.

"I had no idea it was so late," Susan declared as they hurried toward
the parked automobile. "Mother will be worried for fear something has
happened to us."

"You might telephone."

"It would take me ages to find a 'phone. I'll be home in a minute or
two now anyway."

It had grown quite dark, but although automobiles had been parked close
together near the swimming pool, the girls experienced little
difficulty in locating Susan's car. As they came up to it they
observed that a garage service truck had drawn up to an automobile only
a short distance away. The uniformed garage man was busy changing a
wheel.

"Some poor fellow had a flat," Susan said sympathetically. "Strange I
didn't pick up the nail instead. My luck must be changing."

Penny had paused to survey the service car more critically. The garage
man, aware that he was under scrutiny, gave her a sharp glance. Then
abruptly he threw his tools into a bag, jumped into his truck and drove
away, leaving his work unfinished.

"Quick! See if you can get the license number!" Penny cried.

"I can't. The car is too far away."

"I got the last three numbers," Penny informed with satisfaction.
"--684. I want to write it down before I forget."

Susan supplied pencil and paper from her purse.