Su Qingci, the princess of Changle County, and Shen Yi, the prince of the Marquis of Zhenbei, were childhood sweethearts who became a "couple of pure hatred" due to a misunderstanding and tortured each other endlessly. Su Qingci, who unexpectedly saw the barrage, gradually realized that the tough-tongued Shen Yi hid deep love - hiding paintings in the darkroom and guarding them silently. After experiencing the assassination crisis, Shen Yi sacrificed his life to protect each other, and the dust-laden letters solved the knots in their hearts for many years. The two of them shed their disguises and faced their deepest feelings. From mutual testing to clingy companionship, this happy relationship that began with misunderstanding and ended in true love is full of heartbeat and warmth that is both sweet and sad.