Lin Wan, a top killer in modern times, accidentally died while performing a mission. His soul actually traveled to the ancient frail and sick new emperor Pei Lin, and shared his body with him, starting a wonderful symbiosis of "emperor day and night killing". During the day, Pei Lin used his extraordinary resourcefulness to deal with the forces of the Queen Mother and the Prime Minister in the court, and tolerated the plan; at night, Lin Wan took over the body, bound the "Vicious Emperor System", and was ordered to "harden" the powerful ministers and slap the relatives in the face. He used the ruthless methods and whimsical ideas of a modern killer to clear the obstacles for Pei Lin.
The two people have different memories and rely on a piece of paper to convey information and test each other, from the initial strangeness and alienation to the later tacit trust. Instant noodles are exchanged for information, hot strips are exchanged for feelings, and modern skills and ancient intrigues collide to create a different spark. When the palace change comes, the wisdom of the day and the sharp edge of the night finally merge into one, and together they compose a legend of "Your Majesty, sleep peacefully, I will come tonight." In the end, they not only regained the imperial power, but also became the most indispensable existence in each other's lives.
