In the year 2030, children began disappearing daily without a trace to a world called The Lone Region. The government seems to ignore the problem and not worry about it. Korean orphan Su-Mi Eoh lives in a foster home, not knowing of the mysterious force threatining kids her age. When she is deceived, sent to Grallo city, and forced to become a soldier, Su-Mi faces all odds to survive. Meanwhile, Angel Hunt is an international student from America studying in Seoul with her older sister Lizzie. One day, she and several other Korean students are placed in a group to participate in an unknown trial. After being given an ability, she learns about magic, fighting, and the past itself.

Princess Maria is the youngest daughter of the King. Unlike her sisters, she's generous, kind, and smart. When Maria is chosen to fight in war as "Prince Mark of Rosma", the army falls into a massacre and her father goes missing. Now a prisoner of war, Maria is eventually taken in by Prince Alaric and Commander Zeke who knows more about the world than she does. To get her kingdom back and learn the truth about her past, Maria needs to step up and become the inner warrior she's meant to be.

Prince Sky had been imprisoned in the palace ever since his family died. He hopes of seeking revenge and aid. Luna Spade is a Labian citizen, but she wants people to see there's more to her than just killing. Two kids from different kingdoms cross paths and have to rely on each other to bring peace to their land.