Blind piano tuner Lu Xian, carrying his assistant, is invited to an old mansion to tune a piano, accidentally stumbling upon Gao Jun coercing the paralyzed Gao Songbai into signing a blueprint transfer agreement. Faced with Gao Jun's strict guard and arrogant obstruction, the visually impaired Lu Xian relies on his extraordinary sense of hearing to acutely capture abnormal vibrations coming from behind the old piano and bookshelf. The brass scale keys hidden deep in the piano belly pull at unknown mechanical mechanisms. Can Lu Xian break the wall, solve the puzzle, and guard the old man's hard work amidst the step-by-step pressing game? The suspense is about to be revealed.