Saintess Isolde is unexpectedly bound by a soul contract to Kiyan, a noble of the night. Forced to work together despite mutual distrust, they uncover Archbishop Valerius's plan to create a false god through forbidden chimera experiments. Hunted by the church and shaken by betrayal, they must cross the boundary between light and darkness—and confront their growing forbidden desire—before a bloody coronation consumes the realm.