Deserts are spreading. Nearly 40% of the earth's land surface is now at risk of desertification, and roughly 12 million hectares are lost to it every year, pushing millions of people to abandon their homes. This episode of the Earth's Furies series follows scientists studying how a desert actually forms, from the mechanics of soil degradation to the physics of how sand dunes migrate across landscapes over time. Field footage takes viewers to affected regions where farmland has turned to dust and communities have had to relocate, paired with researchers explaining the drivers behind the process, including drought, overgrazing, and poor land management. The film also looks at mitigation efforts already underway, from tree-planting barriers to soil rehabilitation projects, and asks how much of the damage can realistically be slowed or reversed. Narration stays factual throughout, letting the scale of the numbers and the on-the-ground footage of cracked earth and drifting sand make the case for how much land is at stake.