Neil Oliver and the team take a journey around the coast of the British Isles. While travelling from Felixstowe to Margate, Neil explores the story of the munitions ship Richard Montgomery, which sunk in the shallow waters of the Thames estuary and could explode with a terrifying force that would devastate the coast. Alice Roberts savours the sea salt at Maldon, and Miranda Krestovnikoff goes in search of the Thornback ray, an exotic species that feeds on the seabed close to the capital.