Half a billion years ago, Australia forms the coastal edge of the supercontinent Gondwana: the oceans are crowded with strange animals while the land above the waterline is nearly empty. Host and director Richard Smith traces how that balance flips, starting with the arthropods, scuttling ancestors of scorpions and millipedes, that become the first creatures to crawl onto the shore. Plants follow, spreading green across a landscape that had been bare rock and sand. Underwater, armor-plated fish are busy testing new equipment: teeth, jaws, sexual reproduction, and lungs, innovations that eventually let four-legged animals haul themselves onto dry land. The film uses Australia's own fossil beds as evidence throughout, and it does not skip the setbacks: the end-Ordovician extinction wipes out roughly 85 percent of marine species, including the once-dominant trilobites, resetting much of what came before. By the close, the ocean's inhabitants have gained a foothold on land, and the planet is being remade from the coastline inward.