What happens when you really get under the skin of the world around you? Everything that surrounds us - and we ourselves - are made of molecules, constructed from a limited set of elements that can combine to form an almost limitless kaleidoscope of possibilities. Dr Kathryn Harkup reveals the inner lives of the invisible molecules that make up our world, ranging from the fundamental to the frivolous; via the psychedelic effects of caffeine to the deadly march of CO2 emissions. This is a book about the stories of discovery, the quirks of science and of human history that have enhanced our appreciation and understanding of the world.