Sir George Porter delves into the link between food and energy in relation to sunlight. A cake is used to demonstrate how we get energy from our food with an explanation of how this happens. George also looks at how various catalysts aid this, by describing what they are and how they work. There is also a selection of plant-based experiments which explain how light helps fuel energy and photosynthesis, and a demo illustrating 'cold light' that female fireflies produce.