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!

As Yona continues to read Su-won's mother's journal, she uncovers secrets about the Crimson Dragon King's bloodline! What's more, Yona discovers the series of events that led to the lethal animosity between her and Su-won's parents... The fates of Kashi, Il, Yon-hi, and Yu-hon are sewn together with the thread of revenge!