Stefan's journey begins with the E number colours. Stefan discovers why these chemicals don't just affect the look of our food but its taste as well. He learns what the colour in some of our cakes and sweets has to do with insects and flamingos and why some of the E number colours could have side-effects. Stefan also delves into the world of flavourings and reveals why eating monosodium glutamate could be no worse for you than eating cheese or mushrooms. He also gains rare access to the magical world of the flavourings industry which can transform your food beyond recognition. His final test sees him using E numbers to get vegetable-hating kids to eat their first brussel sprouts in years.

In this episode Stefan looks at E number preservatives. He discovers one that keeps deadly bacteria out of our bacon, one that can double up as an explosive, and he even discovers an E number that the entire human race can't live without. And in a true act of immersive reporting, Stefan even attempts to extract several E numbers from his own body. As if this weren't enough, he then makes a cake out of them.

Stefan looks at E number sweeteners used to replace sugar and also learns about the chemicals used to hold our food together. He looks at how E numbers keep the ice out of ice cream, discovers the seaweed that's an E number found in our cakes, and even undergoes MRI scans in an attempt to discover whether E number sweeteners are clever enough to fool our brains.