窃声

窃 = 切 + 穴 : The Queen of Hearts (qi) is stealing (窃) the cave paintings (穴) in the elevator's bathroom (e4) by cutting (切) them off the wall.

声 = 士 + 尸 + 丨 : Sherlock Holmes (sh) hears the terrifying sound (声) of bone (丨) on stone in front of the engine ((e)ng1), and he's sure that there must be a ghost (尸). Indeed it's only the bachelor (士) who wants to scare Sherlock.