In a world encased in ice, the surface has become a frozen wasteland where a small ruling elite wields absolute power after obtaining a UFO and the advanced technology within it. Long ago, part of humanity fled the encroaching cold by descending into the deep sea, where they adapted and evolved into a distinct undersea civilization. Now, these ocean-dwelling humans, having transformed in isolation, launch a war to reclaim the frozen surface and seize dominance from those who remain above. Caught between these two warring factions is a spy from the surface who becomes entangled in the escalating conflict. The story unfolds as a science fiction spy thriller and war drama, following the protagonist's journey through the treacherous cold of the surface and the alien depths of the ocean, where the temperature remains a constant four degrees Celsius even in this global ice age. The struggle for control of the UFO and the fate of the planet drives a battle not only for territory but for the very definition of what it means to be human.