The Locked Pencil Case

Lila came to school on Monday with a new pencil case. It had a small silver lock on the front. The lock had a four-digit code dial.

"Why is your pencil case locked?" said Pim.

Lila looked uneasy. "It just is."

"What's inside?"

"My pencils."

"Why do your pencils need to be locked?"

Lila said nothing. She turned and went to her seat.

Pim wrote in his notebook:

Case 9: The Locked Pencil Case.

He thought about it during the spelling test. He thought about it during break. He thought about it during the bit where they had to draw a leaf.

There were two possibilities, he decided. Either Lila had something inside that she did not want anyone to see (the secret theory), or someone had been taking things from her pencil case (the theft theory).

After lunch, Pim sat next to Lila very carefully.

"Lila," he said, "are you locking it because someone has been taking your pencils?"

Lila did not look at him. After a long moment, she nodded, very small.

"Who?" said Pim.

"I don't know. Things keep going missing. I had three good pencils. Now I have one. I had a sharpener. It's gone. I had stickers."

"And you don't know who took them?"

"No."

Pim nodded. He understood. The locking was not the case. The case was: who?