We buy a staggering 90% of our food from supermarkets, and they have a huge influence over our lives. Gregg Wallace goes behind the scenes with Britain's biggest food retailers over the course of a year to discover how they source, make and move the food we find on the supermarket shelves. He has exclusive access to the buyers, product developers, food technologists and backroom teams, and gets the insider's guide to how much they know about us and our tastes.