The Secret of the Old Mill by Franklin W. Dixon

When he took his place in class that morning, Frank Hardy glanced over at the desk, two aisles away, where Callie Shaw was sitting.

Callie, a brown-haired, brown-eyed miss with a quick, vivacious manner, was one of the prettiest girls attending Bayport high school. She was Frank's favorite of all the girls in the city, and each morning he glanced over at her desk and never failed to receive a bright and fleeting smile that somehow made the dusty classroom seem a trifle less drab and monotonous, and when she was not there it always seemed that the day had gotten away to a bad start.

She was there this morning, but she was gazing soberly at her books and she failed to return Frank's glance with her usual smile. This was something so utterly extraordinary that Frank gazed at her, open-mouthed, for a second or so until, recollecting himself, he turned to his own books and proceeded to spend much of the time until recess in a state of helpless wonderment. Like the average boy under such circumstances, he racked his brains trying to recollect what he could have done that might have offended Callie. But there seemed to be no solution to the mystery.

Perhaps she had heard of how he had been fooled by the stranger yesterday. Perhaps she felt contempt for him because he had been so easily outwitted. This was one of his wild surmises, but he rejected it because it was not like Callie to be angry about anything unless there was good reason for her displeasure. At last he gave it up and tried to dismiss the matter from his mind, but several times during the morning he cast covert glances in her direction.

But Callie was plainly worried and downcast. She seldom raised her eyes from her books, she answered the teacher's questions in a most abstracted manner, and altogether it appeared that there was something on her mind beyond schoolwork.

When recess came she walked slowly out of the room, not mingling with the other girls. Frank saw her go outside toward the campus, where she sat down on the grass by herself, watching an impromptu basketball game and declining all requests to join in the fun.

He went over to her and flung himself down on the grass beside the girl.

"What's the matter, Callie?"

She looked up at him and smiled faintly.

"Hello, Frank, where did you drop from?"

"I've been sitting right across from you in school all morning and this is the first time you've noticed that I'm alive."

"I'm sorry, Frank. I didn't mean to be rude. I've got something on my mind this morning, that's all."

"Trouble?"

She nodded.

"What about?"

"Money."

He was puzzled by this remark. Callie lived with her cousin, Miss Pollie Shaw, the proprietor of a beauty parlor in the city, and although Miss Shaw was not rich, she made a comfortable living. Therefore, when Frank heard Callie say that she was worried about money he was naturally puzzled. Callie's parents lived in the country, but they sent their daughter frequent remittances to pay the expenses of her education in Bayport.

"What's the matter? " he asked. "Didn't your allowance come?"

"No, it isn't that. I'm all right. It's Pollie. She lost some money. More than she could afford."

"Lost some? How was that?"