Su Jinshu, the legitimate daughter of the General of Dingyuan's household, has her identity stolen by Lin Xiyue, a woman who has traveled from the modern world. Branded an impostor, Su is even handed over by her biological father to a sixty-year-old eunuch. Driven to despair, she considers ending her life. Meanwhile, Lin Xiyue finds the Gaokao too exhausting and gives up her chance to return to the modern world through her system. Seizing this opportunity, Su Jinshu trades souls with her and takes over the body of Lin Xiyue, a struggling high school senior. Starting from scratch, she studies tirelessly, going from knowing nothing to solving practice problems day and night. Against all odds, she rises to rank thirteenth in the entire city and earns admission to a top university, finding both academic success and love along the way. At last, she takes control of her own destiny. Meanwhile, Lin Xiyue, left behind in ancient times, is trapped in the inner quarters, suffering humiliation after humiliation. Regretting her choice too late, she eventually wastes her entire life behind the palace walls.