Xiaotao and I re-entered the classroom. I sniffed at the walls, but the wallpaper appeared to be scented, so I couldn’t detect the presence of any human body inside. 

“Are you sure the rich lady is hidden here?” asked Xiaotao. “Wouldn’t she be easily discovered here?”

I tore down the wallpaper and a layer of soundproofing material was exposed.

“With the soundproofing material,” I said, “no one would suspect anything.”

Xiaotao ripped the wallpaper on the other wall down and was shocked. “Song Yang!” she shouted. “There’s...