In this episode Jimmy asks, 'What's really in my sandwich?' He attempts to discover what they do to supermarket bread to make it stay soft for over a week, while home-baked bread goes stale and rock hard after just a few days.He wonders why square processed cheese slices are so popular - can it really be because they are so conveniently bread shaped? Why do they melt differently to 'normal cheese'? And if processed cheese only contains 60% cheese, what are the other ingredients?To copy the factory processes, Jimmy makes supermarket bread in a metal dustbin, and square processed cheese slices using a tin bucket and an electric drill.To complete his investigation Jimmy leaves the barn to find out how one bagged-salad producer in Wiltshire goes to herculean efforts to ensure we never find a caterpillar or bug in our bag, and how waste bananas are being used in Hertfordshire to grow tomatoes out of season.