David starts his journey in a forest near the home he grew up in Leicester, where a fossil discovery transformed our understanding of the evolution of complex life. He then travels to Newfoundland and the Australian outback, where he unearths the earliest forms of animal life to exist on the planet.

Attenborough explores the Burgess Shale in Canada’s Rocky Mountains, where there is fossil evidence of an event 542 million years ago which saw animals increase in number, diversity and size as never before. These ancient rocks reveal the world’s first large predator, the first defences and the emergence of an animal group that would conquer the oceans: the hard-shelled arthropods.