The Gray family has two daughters—Luna Gray, whose mother is the matriarch, and Stella Gray, the daughter of the secondary wife. As the Grand Duchess, Luna cannot seem to get pregnant, so she asks Stella to replace her and get pregnant with the Emporer’s child because Stella resembles her a lot. Pretending to reject her request, Stella then enters the palace with the pendant left by her deceased mother and starts plotting her revenge.
In the year 2200 AD, the two major powers in the Earth's orbit, "Xuan Yue" and "Su Yue," ended their more than 50-year Cold War and were about to sign the "Dual Moon Peace Agreement." However, a series of terrorist attacks suddenly occurred in Xuan Yue's circular colonial city called "New Moon City," indicating that fragile human civilization is once again facing a great crisis.