A Hollow Knock

I swung off the bed and dashed straight into the narrow slot behind the bedroom door! Ooooh, it was so dark and tall back there! I stretched my long arm way up, wedging my shoulder against the wall, and tapped my knuckles against the painted wood. Thump... clack! A loud, hollow bounce echoed through the stillness! I paused, grinning into the gap, then tapped it again faster. The hinge groaned back with a tiny squeak, answering me in the quiet room.