I left my daughter with my parents during a business trip. Two days later, she disappeared at the mall. My parents said, “we only looked away for a moment.” Ten years later, while cleaning out my grandmother’s house, I found a strange vent in the wall. I leaned in and heard a little girl humming from inside.

At first, I thought it was decorative—some weird old-fashioned airflow thing. But when I crouched down and brushed the dust away, I noticed something odd.

The paint around the edges was worn.

Not chipped.

Worn.

Like fingers had brushed against it. Over and over.

I told myself it was nothing. Old houses had secrets. That didn’t mean they were important secrets.

I leaned closer.

That was when I heard it.

A child, humming.

Soft. Careful. Almost shy.

The tune was wrong—not a song I recognized, but something improvised, looping back on itself. A tune made to pass time. A tune made when you think no one is listening.

My knees hit the floor so hard I bruised them. I pressed my ear to the vent, heart pounding so loudly I was sure it would drown out the sound.

But the humming continued.

I whispered my daughter’s name.

The humming stopped.

For a long moment, there was nothing but my own breathing echoing in the narrow space behind the wall.

Then, from somewhere deep inside the vent, a small voice whispered back.

“Mom?”

I don’t remember standing up. I don’t remember crossing the room. I only remember tearing the vent cover off with shaking hands, metal screeching against metal.

Behind it was darkness.

Not the flat darkness of a wall cavity. This was deeper. It stretched back farther than it should have, the edges swallowing what little light there was. The air smelled stale and sweet, like dust and something faintly rotten.

“Sweetheart?” I whispered. “Can you come closer?”

There was a rustle, like fabric brushing against wood. The humming started again, quieter now.

“I can’t,” the voice said. “It gets mad when I move.”