Kang Pi-o is a rigid, technically flawless piano prodigy whose life is defined by severe performance anxiety, an illegitimate family status, and intense pressure from his overbearing mother. His controlled world fractures when he forms a deep musical bond and fierce rivalry with classmate Choi Jeong-yo, who mysteriously vanishes during a Prague competition that Pi-o wins. A decade later, a highly successful but psychologically ruined Pi-o is cornered by elite conductor Luca Domenico (a disguised Jeong-yo seeking vengeance), who forces him to perform a traumatic concerto titled "Nemesis". The cycle of guilt shatters when Pi-o learns that his own mother masterminded Jeong-yo's kidnapping to eliminate the competition, driving a devastated Pi-o to retire and sell his piano. After sharing one final, cathartic four-hands duet that costs Jeong-yo his already injured hand, the series jumps three years into the future, concluding as Pi-o tracks a musical trail to a Czech Republic church to peacefully reunite with Jeong-yo, finally finding the pure joy of music free from their toxic past. They then go to the town together and confess their feelings to each other.
