Princess Yona lives an ideal life as the only princess of her kingdom. Doted on by her father, the king, and protected by her faithful guard Hak, she cherishes the time spent with the man she loves, Su-won. But everything changes on her 16th birthday when tragedy strikes her family! Feeling ill from the Crimson Illness, Su-won is unable to attend a conference with a South Kai delegation. Yona goes in his stead and manages to hold her own, but what will she do when someone blames her for the death of one of the delegation members?!