Neil Oliver embarks on a journey to explore the story of how today's Britain and its people came to be, forged over thousands of years of ancient history. He joins a team of archaeologists in the tidal mud banks in South Wales to examine 8,000-year-old footprints, and bones in a West Wales cave dating back to 33,000 years. The historian also reveals how, as the climate became warmer and the ice melted, Britain became an island, a fate that was sealed following a cataclysmic tsunami around 6,000 BC