Zhao Ning'an, the eldest princess of Zhaoyang, and Xie Yanci, the great general who guards the north, are deeply in love. But their fates clash, and both die in a palace coup.
On the road to the Underworld, Xie Yanci willingly gives up reincarnation to protect Zhao Ning'an, whose soul has shattered. He enters the Underworld as a soul-guide, carrying a lantern to guide spirits and keeping watch over the River of Forgetfulness.
To gather the three souls and seven fragments of Zhao Ning'an scattered across the mortal realm, he journeys between the worlds of the living and the dead for a hundred years. He experiences seven cycles of joy and sorrow amid the mortal world, trading the deepest devotion for the deepest grief, all to retrieve each remnant of her soul.
The day her soul is restored, all memories of their past awaken. She would rather remain trapped forever by the River of Forgetfulness than be parted from him. But at the cost of saying goodbye forever, he forces her into reincarnation, asking only that she live a peaceful life.
She refuses Meng Po's soup and reincarnates, determined to find him. But after giving her heart to the wrong person, he erases all her memories, leaving her lost in oblivion.
By the River of Forgetfulness, the lantern-bearer stands eternally on watch; in the mortal world, those he has guided enjoy peace year after year.
In the end, this love that crossed the boundary between life and death costs him eternal loneliness in exchange for her carefree life.
