The Great Queen Seondeok is a biopic of Queen Seondok, who was born a princess and later became the ruler of Silla, leaving behind many shining achievements. During the Three Kingdom period of Korea, Deokman (Queen Seondeok's childhood name) was born as a twin but she was abandoned as a baby. She was later brought back to the Silla palace where she joined forces with her twin sister Princess Chonmyong to oppose Mi-shil who wanted to seize power. Mi-shil devised sinister plans to have the two Silla princesses exiled from the kingdom and in a secret feud, Princess Chonmyong was assassinated by Mi-shil. But being very intelligent, Princess Deokman enlisted the help of General Kim Yusin and eliminated her archenemy Mi-shil. She became the first female ruler of the Silla kingdom.