In a heroic act at the age of twelve, Su Nian exchanged a crescent scar for the promise of young Gu Tingshen, but his sister Su Qing pretended to be the "White Moonlight" he had cared about for many years. Many years later, Su Qing suffered from leukemia. In order to raise medical expenses, Su Nian was desperate and signed a cold contract to marry into the Gu family as a "substitute" and live as her sister's shadow.
Gu Tingshen's indifference, Lin Weiwei's calculations, the humiliation of the slap, and the sudden attack of terminal illness crushed her life into pieces. She hid the diagnosis certificate for terminal gastric cancer and silently fulfilled the contract, just to earn a living for her sister. Little did she know that the silver chain engraved with the word "Nian" and the painting with the word "Nian" hidden in it were all keepsakes that Gu Tingshen had treasured for many years.
When medical records were tampered with and the truth was covered up, Su Nian reached a desperate situation amid misunderstandings and pain. It wasn't until Mrs. Gu's advice and Su Qing's confession that Gu Tingshen realized that he had made a mistake for many years. The substitute he despised and hurt was the girl who saved him and loved him back then.
The belated guilt could not save his life, so Su Nian left with the regret of "Don't admit your mistakes in the next life." Gu Tingshen dedicated the rest of his life as a sacrifice, established a foundation, traveled old roads, guarded her ashes, and used his life to fulfill the promise of "recognizing her in the next life." This misunderstanding that spanned twelve years finally wrote a substitute tragedy with bone-crushing affection and endless regret.
