After suffering a fall from grace, a photographer returns to her hometown and bumps into her childhood friend — rekindling an unfinished romance.

Set during the turbulent time of the fall of Goryeo and the founding of Joseon, two former friends face-off against one another over a woman and the future shape of the nation.

Kingdom of Goguryeo, ancient Korea, 645. The ruthless Emperor Taizong of Tang invades the country and leads his armies towards the capital, achieving one victory after another, but on his way is the stronghold of Ansi, protected by General Yang Man-chu, who will do everything possible to stop the invasion, even if his troops are outnumbered by thousands of enemies.

Nam Shin is a son from a family who runs a large company. After an unexpected accident, he falls into a coma. His mother Oh Ro-Ra is an authority on brain science and artificial intelligence. She creates an android named Nam Shin III which looks like just like her son Nam Shin. The android pretends to be Nam Shin and he has a bodyguard So-Bong.

The fictional story begins after the execution of real-life North Korean general Jang Sung-taek. One day an order comes down from North Korea, reactivating erstwhile spy Park Hye-rim who has spent decades in South Korea as an ordinary housewife. She is given the mission to turn and bring in her own son, Kim Seonu. Cool-headed, quick-witted genius Seonu is an information analyst on North Korea working for the NIS. His girlfriend Yoon-jin is a tour guide for Chinese tourists who cannot speak Chinese, and they fell in love when Seonu helped her translate. Hye-rim is suddenly forced to choose between her son and country, and risks her life to see the choice through.