Lee Jae-ha (Lee Seung-gi) is the king's younger brother. He exudes a rich family atmosphere, sophisticated humor and outstanding appearance, but his heart is completely vulgar. As the king of ideas, his lifelong wish is to never marry and enjoy the wealth and beauty in the palace. But he received an unexpected proposal from his brother to "get married", and the object is a North Korean woman? Why, crazy! The legendary female instructor Kim Hang-ya (Ha Ji-won) who is responsible for teaching the most elite troops in North Korea is versatile in physical strength, training, and tactics, but as a woman, she has never tasted the taste of love after she was over 30. She was ordered by the organization to use marriage as bait to promote peace between North and South Korea. She joined the party, but she didn't expect that the object was the lazy Lee Jae-ha! The two developed a tense and interesting love story...