The King 2 Hearts is set in a fictional modern day where South Korea is governed by a constitutional monarchy. Lee Jae Ha is a handsome and materialistic crown prince that doesn't care about politics. His life turns upside down when his brother forces him to join a team consisting of soldiers from North and South Korea to join a World Officers Competition.

Kim Hang Ah is a North Korean special forces agent who doesn't have experience in love or dating. Although she is tough and brave, she has a warm heart and naive, wishing to get married and live life peacefully. When her comrade convinces her to join the Korean team for WOC, she meets the cocky prince and they immediately start a love-hate relationship. Things take a drastic change when they find out that their families have been planning for their eventual wedding...