How did life storm the beaches and dominate planet Earth? Ancient Australian fossils offer clues. While the oceans were teeming, the world above the waves remained an almost lifeless wasteland -- until the Silurian period, when the conquest of the land began. Host Richard Smith introduces Earth's forgotten pioneers: the scuttling arthropod armies that invaded the shores and the waves of green revolutionaries whose battle for the light pushed plant life across the face of a barren continent. Join NOVA's prehistoric adventure as four-legged animals walk onto dry land, with the planet poised for disaster.