Documentary examining the world of one of Britain's biggest and best-loved chocolate makers. Behind closed doors at Cadbury's Bournville plant, a team of scientists struggles to meet the biggest challenge the company has faced for a century - to dramatically cut sugar from its Dairy Milk recipe. Can the new bar match up to its beloved predecessor? Elsewhere in the factory, new flavours of chocolate are put into production, with wacky recipes invented by lucky members of the public