Something awaits them 8,000 feet under the sea…

In Sector 7, an underwater oil field located south of Jeju Island, Hae-jun is working as a marine equipment manager on an oil prospecting ship called Eclipse. Joining the crew later is Jeong-man, a former colleague of Hae-jun's father, assigned to Eclipse as captain. Though his job is to oversee the withdrawal of the ship, he suggests conducting some drilling one last time.