In 1597, the Joseon Dynasty was in crisis. The main force of the Joseon Navy suffered a huge blow with the demotion of General Yi Sun-sin (played by Choi Min-sik). Military discipline collapsed and only a few warships were left. The Japanese pirates took the opportunity to send Wakizaka Yasuharu (played by Cho Jin-woong) to cooperate with the pirate army of the dreaded "Pirate King" Raishima Tsuneso (played by Ryu Seung-ryong) to attack together and they were bound to capture Hanyang. At the critical moment, Yi Sun-sin decided to lead the remaining dozen warships to the Myeongnyang Strait to fight the Japanese pirates. Yi Sun-sin first sent his subordinate Ren Junyong (played by Jin Goo) to the enemy to meet the undercover Junsha (played by Otani Keihiko), and then revitalized the army, with the spirit of "the brave live, the fearful die", calling for a decisive battle with the Japanese pirates. At the beginning of the decisive battle, Yi Sun-sin led the way, defended the Blood Island, and defeated several advance troops of the "Pirate King". At the critical moment, Ren Junyong's mute wife (played by Lee Jung-hyun) understood his lip language and played a role, allowing Yi Sun-sin to successfully rescue the ship. In the end, the military and civilians worked together to severely damage the Japanese fleet, creating a famous battle in the history of world naval warfare where the few defeated the many.