Penicillin is the drug of the twentieth century. It was the first of the antibiotics that, for decades after the Second World War, underpinned a popular belief that the threat of infectious disease had at last met its match. With the emergence of 'superbugs' these hopes have faded. Robert Bud pulls these different but conjoined stories into a compelling narrative: using a wealth of new research, he sets the discovery and use of penicillin in the broader context of social and cultural change across the world. His book will be of great interest to historians, scientists, and anyone wishing to understand this drug's seismic impact on our lives.