Geologist Nick Isles traces the Great Rift Valley across 3,700 miles of East Africa, from the volcanic highlands where early hominins evolved to the Afar Depression, where the crust is splitting open and a new ocean is slowly forming. He walks the rift's fault lines and lakebeds, connecting the same tectonic forces that carved this landscape to the climate shifts that pushed our ancestors out of the trees and onto two feet. The film moves through Ethiopia, Kenya, and Tanzania, visiting sites tied to key fossil discoveries and explaining how shifting rainfall and volcanic activity created the mosaic of grassland and forest that shaped human evolution. Isles talks with scientists working the rift today, including researchers monitoring the Afar's spreading ridges as a live example of continental breakup. The throughline is geology as biography: the same violent, ongoing process of Africa tearing itself apart is presented as the environmental engine that produced humanity itself.