Emily was a curious first-grader who loved solving mysteries. One night, as she was getting ready for bed, she heard a strange sound coming from under her bed. It was a faint, whistling noise that seemed to move around.

Intrigued, Emily slowly bent down and peeked under the bed. To her surprise, she didn't see anything out of the ordinary. But the whistling continued, and it was starting to give her the chills.

Determined to get to the bottom of this mystery, Emily decided to investigate further. She grabbed a flashlight and carefully looked around the space under her bed. As she shone the light, she noticed a small, furry creature huddled in the corner.

The creature turned out to be a tiny mouse, who had found a cozy spot under Emily's bed. The mouse was trying to keep warm by whistling softly. Emily giggled, realizing that the mysterious sounds had a perfectly harmless explanation.