On the eve of her wedding, Qin Yan is kidnapped by the Qin family and sent overnight to the imperial palace in the capital, where she becomes a stand-in for her elder sister, Qin Xin, in the emperor's bedchamber.
By day, Qin Yan is a low-ranking palace official whom everyone looks down on. By night, she becomes the young emperor's treasured favorite.
Qin Xin relies on her to receive the emperor's nighttime favors, becoming the most beloved woman in the Six Palaces and growing unbearably arrogant.
Long since numb, Qin Yan has had everything taken from her, until she becomes pregnant with the emperor's child.
Driven by a mother's love, she awakens and begins plotting how to replace Qin Xin and become the winner in the imperial harem.
Xiao Heng has always believed that Qin Xin, whom he has watched grow up since childhood, is the woman who truly matches his ideal.
But one night, after returning from a personal military campaign, he hears the woman beside him sobbing in her sleep.
As the highest-ranking imperial consort, she is the most honored woman in the realm after the empress, yet she wants to die.
Xiao Heng is stunned. He believes the affection he has shown Qin Xin has long surpassed what he has given any other woman in the harem. Why, then, would she want to take her own life?
So he begins discreetly investigating everything about Qin Xin, including the half-sister she suddenly brought into the palace.
Before long, he discovers the truth: the captivating beauty who enthralls him every night is actually the unremarkable-looking palace official he sees by day.
Xiao Heng suddenly finds it all rather amusing. He will not forgive the Qin sisters, so he begins a game of cat and mouse.
He originally planned to send both sisters to hell after Qin Yan gave birth to his first child. But later, he realizes that he can no longer live without the enchanting figure who appears each night.
So Xiao Heng begins carefully plotting to raise Qin Yan to the highest position in the imperial harem.