The film mainly tells the story of changing the fate of more than 400 Korean civilians who were forcibly recruited by the Japanese army on Warship Island during the Japanese colonial rule. In 1945, at the end of the war, rumors abounded, and during a time of turmoil, Li Jiangyu (played by Huang Zhengmin), head of the Jazz Orchestra of the Peninsula Hotel in Beijing, took his only daughter Suji (played by Kim Soo-an) and members of the orchestra, under Japanese rule. The suffering Suja (played by Lee Jung Hyun) and other Koreans were deceived by the lie that they could make money and went to Japan, but they arrived at the warship island where the Koreans were forcibly requisitioned. In the 1,000-meter-deep mine under the sea, they endured the danger of gas explosions and were forced to work. Li Jiangyu tried every means to protect his daughter on the warship island, and Cui Qixing and Mo Zi also used their own methods to survive the painful days. After the war, the OSS of the U.S. Strategic Intelligence Force secretly instructed Park Moo-young (Song Joong-ki), an important member of the North Korean Independence Army, to rescue Yoon Hak-cheol (Lee Kyung-young), a presidential candidate lurking on the warship island. In order to cover up all the crimes committed against the Koreans on the warship island, the Japanese decided to blast the mines where the Koreans worked. In a critical situation, Park Wuying rescued Yin Xuezhe with difficulty and revealed his identity. The North Koreans headed by Park Moo-young, Li Jiangyu, Cui Qixing, etc. were determined to escape from the warship island, but the director of the mine, who was vaguely aware of the inside story, desperately pursued and killed them in order to cover up all the secrets of the warship island