The metal of modernity, spawning icons from the Chrysler Building to the Harley Davidson, this colourful element is the key ingredient in stainless steel and leather. But chromium also has a dark side - one brought to public attention by Erin Brockovich. Presenter Justin Rowlatt speaks to Erin - the real Erin - and he also travels to the Savoy Hotel in London and to the world's first steel town of Sheffield, to tell the story of chromium's biggest modern use. Show less