Monroe was a curious fourth-grader who loved solving mysteries. One day, his best friends, Bill and Sam, came to him with a problem. Their teacher, Mrs. Johnson, had lost her prized notebook, and they suspected someone had stolen it.

"We have to find that notebook!" exclaimed Monroe. "Let's investigate and see if we can crack the case."

The three friends began their search, scouring the classroom and asking their classmates if they had seen anything suspicious. They checked the lost and found, the school office, and even the janitor's closet, but the notebook was nowhere to be found.

As they were about to give up, Monroe noticed a small piece of paper on the floor near Mrs. Johnson's desk. It was a torn-off corner of a page, and it had a name written on it: "Sam".

"Sam, did you write your name on this piece of paper?" Monroe asked, his eyes narrowed with suspicion.

Sam's face turned pale. "No, I didn't. I haven't been near Mrs. Johnson's desk at all."

Bill and Monroe exchanged a concerned look. "Then who did?" Bill asked.

The three friends decided to investigate further, determined to uncover the truth and find the missing notebook.