Britain eats more fast food than any other country in Europe. It looks good, tastes good, and it's cheap. But the real cost never appears on the menu. Eric Schlosser visits the lab that re-creates the smell of strawberries; examines the safety records of abattoirs; reveals why the fries really taste so good and what lurks between the sesame buns - and shows how fast food is transforming not only our diets but our world.