Aiden, a curious fifth-grader, loved solving puzzles and mysteries. One day, as he was walking home from school, he stumbled upon a peculiar scene. His neighbor, William, was frantically searching the ground, patting his pockets, and muttering under his breath.

"What's wrong, William?" Aiden asked, approaching his friend cautiously.

"Oh, Aiden! I can't find my house keys anywhere," William exclaimed, his brow furrowed with worry. "I just had them, and now they've disappeared!"

Aiden's eyes lit up. This was the perfect opportunity for him to put his detective skills to the test. "Don't worry, William, I'll help you find them!" he said, determined to get to the bottom of the mystery.

The two boys began searching the area, retracing William's steps and looking under bushes and behind nearby benches. As they searched, they ran into two other neighbors, Lisa and Nancy, who had also lost their keys.

"This is strange," Aiden said, his mind racing with possibilities. "Someone must have taken all of our keys. We need to figure out who and why."