In the Joseon Dynasty, two friends who grew up together — one the master and one the servant — reunite post-war as enemies on opposing sides.
The Imjin War reaches its seventh year in December of 1598. Admiral Yi Sun-shin learns that the Wa invaders in Joseon are preparing for a swift withdrawal following the deathbed orders of their leader Toyotomi Hideyoshi. Determined to destroy the enemy once and for all, Admiral Yi leads an allied fleet of Joseon and Ming ships to mount a blockade and annihilate the Wa army. However, once Ming commander Chen Lin is bribed into lifting the blockade, Wa lord Shimazu Yoshihiro and his Satsuma army sail to the Wa army's rescue at Noryang Strait.
After the assassination of President Park, martial law has been declared. A coup d'état bursts out by DefenseSecurity Commander Chun Doo-gwang and a private band of officers following him. Capital Defense Commander Lee Tae-shin, an obstinate soldier who believes the military should not take political actions, fights against Chun Doo-gwang to stop him. The conflict between the two grows while military leaders are holding their decision and Defense Minister is gone. In the midst of chaos, the spring of Seoul that everyone longed for heads to unexpected direction.
Han Ji-hyuk, an NIS agent gone MIA, returns after one year to join a new team as he searches for his lost past.
All unemployed, Ki-taek's family takes peculiar interest in the wealthy and glamorous Parks for their livelihood until they get entangled in an unexpected incident.
A young girl named Mija risks everything to prevent a powerful, multi-national company from kidnapping her best friend - a massive animal named Okja.