Welfare home boy Su Xiaoman is optimistic and talkative. After being adopted by the Su family, he meets sister Su Wan, who has not opened her mouth for three years. With his nonstop companionship, sincere protection, and music, he bit by bit chips away at his sister's closed-off heart. The brother and sister support each other on campus and on stage, facing misunderstandings and tests, guarding fairness and passion, ultimately letting the sound of the piano be heard and letting each other become true family.