Eighteen thousand years ago the planet's climate flips abruptly, ending a deep freeze that had locked the Earth in ice for millennia. This film tracks what happens next: massive ice sheets begin to melt, pouring fresh water into the oceans and pushing sea levels up by more than a hundred meters over a few thousand years. Coastlines vanish, land bridges disappear, and entire ecosystems that had adapted to glacial conditions collapse or migrate. The film follows the evidence for how this meltdown reshaped the map of the world, drowning low-lying regions and opening new territory elsewhere, while also examining its role in the extinction of Ice Age megafauna like mammoths and giant sloths, and in the movement of early human populations chasing retreating ice and shifting coastlines. Drawing on geological records, ice cores, and fossil evidence, it builds a picture of how one climate shift, sudden by geological standards, remade the physical world humans would go on to inhabit.