Global birth rates are plummeting, reshaping societies from Japan to Europe to parts of South America. Aging populations are straining healthcare and pension systems, while shrinking workforces threaten economic growth. The documentary follows demographers and policymakers grappling with a historic reversal: for the first time, many developed nations face not overpopulation but the opposite problem, too few young people to sustain the old. Some countries are experimenting with immigration and incentives to boost births; others are reckoning with permanent demographic decline.