Three years after the Siberian discovery, Earth's magnetic field begins collapsing at an impossible speed. At the same time, the Sun is approaching a mega-flare powerful enough to devastate an unshielded planet. Kiyoshi Shirane and Lila Manabe discover that the only possible answer lies twelve thousand meters below the sea, where the ruins of Civilization Minus Two and a six-kilometer vessel of Civilization Minus One have waited for ages. Humanity builds the patchwork submersible Wadatsumi and descends into the Mariana Trench with Calvin, Emily, and Dino—the child whose royal blood may be the key to restoring Earth's geomagnetic shield. But the ancient system demands more than blood. The second volume of ±0 Civilization is a story of science, inheritance, family, and the choice that gives overwhelming power meaning.