Four cities pushed to the edge of habitability, each examined in its own segment. La Paz sits above 3,600 meters, ringed by 5,000-meter peaks, where thin air strains every human body and every building project. Yakutsk, the coldest city on Earth, is built on permafrost now thawing under a warming climate, threatening the foundations beneath it. Bangkok is sinking roughly 4 centimeters a year while typhoons intensify and the sea creeps higher, turning water into an existential threat rather than a resource. Hammerfest, the world's northernmost city, loses the sun for two months each winter, and the film documents the toll of that darkness through what researchers call polar stress syndrome. Local residents, engineers, and scientists appear on camera describing how their communities adapt: reinforced foundations, flood barriers, light therapy, oxygen-starved construction sites. The series moves through each location with location footage and expert interviews rather than narration alone, building a picture of how far infrastructure and physiology can be stretched before a city becomes unlivable.