King Il of Kouka, a land said in legends to have been founded by four dragons, has only one remaining heir, a daughter named Yona. She lives a happy life in the palace with her cousin Soo-won, who she loves in spite of her father's opposition to them marrying. Her life is turned upside down when Soo-won murders her father and steals the throne. Yona, with her childhood friend and bodyguard Hak, must retreat to gather allies and reclaim her place as ruler of the kingdom.