Monroe was a curious fourth-grader who loved solving puzzles and mysteries. One day, his best friend Mike came running up to him, his face as white as a ghost. "Monroe, my bike is gone! I left it outside the school, and now it's disappeared!" Mike cried.

Monroe's eyes widened, and he felt a surge of excitement. "Don't worry, Mike. We'll get to the bottom of this mystery!" he said, his voice filled with determination. The two friends set out to investigate, their minds racing with possibilities.

As they searched the school grounds, they noticed Lily, a girl in their class, acting a little suspicious. "Have you seen a bike around here?" Monroe asked her. Lily's eyes darted away, and she mumbled, "I-I don't know anything about a bike."

Intrigued, Monroe and Mike continued their investigation. They soon discovered that Brianna, another classmate, had been bragging about a new bike she had. "That's strange," Monroe thought, "Brianna's family doesn't have much money. Where did she get that bike?"

The boys knew they were onto something, and they followed Brianna home after school. To their surprise, they saw her hiding Mike's bike in her backyard! "Brianna, what are you doing with that bike?" Monroe demanded. Brianna's face turned bright red, and she confessed that she had stolen the bike because she wanted one of her own.

Mike was relieved to have his bike back, and Monroe felt proud of himself for solving the mystery. The three of them agreed to keep the incident a secret, and Brianna promised to never steal anything again. From that day on, the four friends became closer than ever, united by the adventure of the missing bike.