In 1920, when Korea is under Japanese rule the Korean Independence Army’s Hae-chul and his subordinates are carrying out the operation to deliver funds to the Korean Provisional Government in Shanghai. During the operation Hae-chul is reunited with Jang-ha, a young squad commander, whose mission is to defend Samdunja. They unite and trap the Japanese soldiers in Samdunja, soundly defeating them. Now they’re chased by Japanese troops and Hae-chul finds out that Jang-ha’s mission isn’t over yet. A crucial yet dangerous task is still assigned to him.

On the eve of the founding of the Joseon Dynasty, a whale swallows the Emperor's Seal of State being brought to Joseon by envoys from China. With a big reward on whoever brings back the royal seal, mountain bandits led by Jang Sa-jung go out to sea to hunt down the whale. But he soon clashes with Yeo-wol, a female captain of pirates, and unexpected adventure unfolds.