Based during the Qin dynasty, general Meng Yi (Chan) is tasked with escorting Ok-Soo (referred at times as "Concubine Li") (Kim), a Korean princess, back to China to serve as a concubine for Qin Shi Huang, in an attempt to strengthen diplomatic relationships. Along the journey, a Korean warrior (seemingly her fiancé) attempts to seize her back but Meng Yi saves her. Meng Yi protects Ok-Soo through their journey back, while Ok-Soo tends to his wounds. In the process, she begins to develop feelings for him but Meng Yi, while apparently harboring similar feelings for her, steps back reminding her of her purpose of becoming a concubine in the interests of her people and successfully completes his mission. The Qin emperor becomes critically ill later and sends Meng Yi to find the elixir of immortality, the only thing that can save his life. Before leaving, Meng Yi discreetly confesses his feelings to Ok-Soo stating "my heart belongs to you forever" and Ok-Soo vows to await his return. The guards escorting the elixir are ambushed by rebels on the orders of the treacherous prince and chancellor. Meng Yi hands over the elixir to his deputy, Nangong Yan, before dying in the ensuing battle. Although Nangong Yan manages to bring the elixir to the emperor, the prince and chancellor trick Nangong Yan and Ok-soo to test the validity of the elixir and force them to consume the elixir, condemning them to imprisonment in the Qin emperor's mausoleum for eternity.