The number one assassin in the martial world, Zheng Ke, enters the palace to assassinate the current emperor in order to avenge his father's death. Little does he know, a massive conspiracy is about to unfold.
While undercover in the palace, Zheng Ke accidentally swaps bodies with the beloved princess Qi Wanner. Thus, the two of them embark on a journey together to find a way to switch back. As they grow to understand each other, their relationship evolves from suspicion to mutual protection and understanding.
Gradually, they solidify their feelings for each other and join forces to overthrow the treacherous prime minister's rebellion plot...