Wal-Mart is the biggest company on earth, ever. Around 7.2 billion people shop there in a year - more than one visit for every person on the planet. It's expanding across the globe from Brazil to Eastern Europe. And it has the power to change our world... Charles Fishman takes us into the heart of the most successful superstore in history to show how the 'Wal-Mart effect' shapes lives everywhere, whether for overnight cleaners in America, bicycle-makers in China or salmon farmers in Chile. Now Wal-Mart's influence is so great it can determine everything from the design of deodorant to the shape of a town, working practices to market forces themselves, Fishman asks- how did a shop manage to do all this? And what will the ultimate cost of low prices be?