A modern mechanical engineer accidentally travels through time into a female-dominated dynasty, and is bestowed by the female emperor upon the powerless and down-and-out third princess. Originally thinking it would be difficult to escape the fate of a pawn, he discovers that the third princess is unwilling to sink. The two make a covenant: the third princess helps him remove his slave status to regain his freedom, and he uses modern skills to assist the princess in planning and laying out strategies, moving step by step to reclaim the power that belongs to her. A perilous game of imperial power officially kicks off.