with Kim Seung-yoo, upon learning of her father's initial plans to arrange her marriage with him. A harmless prank to sneak a peek at her intended husband spirals out of control as they fall deeply in love with each other, ignorant of the deep and deadly political enmity that slowly develops between their fathers. After Kim Seung-yoo is chosen by the King as a candidate for Prince Consort, Grand Prince Suyang promises Se-ryung's hand in marriage to Shin Myeon, Kim Seung-yoo's best friend. As the truth of her father's machinations and atrocities gradually dawns on her, Se-ryung begins to resist her father's power and Shin Myeon's advances. However, she is trapped by the knowledge that saving Kim Seung-yoo's life means the death of her family, while the price of his life is the cost of saving them. When her father is crowned as King, Se-ryung becomes a Princess, but as she learns more about her father's cruel grasp for power, she battles her loyalty to her family with the love she bears for Seung-yoo, as well as the knowledge that his cause is the right one. Park Si-hoo as Kim Seung-yoo (김승유, 金承琉) As the second son of Kim Jong-seo, a prominent military officer who serves as the Deputy Prime Minister of Joseon, he is a carefree scholar in the Royal Academy, whose main interests are having a good time with the ladies and spending time with his close friends, Shin Myeon and Jung Jong. He meets his match in the spirited Se-ryung, whom he thinks is the Princess, and he is drawn to her from their very first meeting. Not knowing about this deception, it seems to him that the road to love is propitious, especially when the King selects him as the candidate for Prince Consort. As he falls harder for her, his love is put to the ultimate test when he learns that Se-ryung is not the Princess, but rather the daughter of his father's biggest enemy. After Grand Prince Suyang kills his father and brother and sentences him to exile, Seung-yoo escapes and transforms himself into a cold and ruthless assassin. Bent on exacting vengeance for the murder of his family, he steels his heart against his love for Se-ryung, believing that she was party to his downfall. Though Se-ryung's selfless love and bravery moves his heart in the end, he cannot turn his back on