The Invisible Intruder

Summary

I went back to the old family estate for the holidays, only to be caught in a torrential downpour.

Staring out the window, my younger brother suddenly called out to me:

"Bro, look."

"Does it look like there's a silhouette in the rain?"

I looked out, but saw nothing.

A few minutes later, my younger sister's voice came from the bathroom:

"I'm showering! Stop trying to open the door!"

But my brother and I were clearly in the living room.

Only outside the bathroom door, there was a trail of muddy footprints...