This episode covers the 1945 Nobel Prize in Physiology or Medicine, which was awarded to Alexander Fleming, Ernst Chain, and Howard Florey. The Nobel Assembly at the Karolinska Institute chose to give Fleming, Chain, and Florey the award “for the discovery of penicillin and its curative effect in various infectious diseases”. Topics include Fleming’s completely accidental discovery of penicillin, how Chain and Florey turned penicillin into a global wonder drug, and some of the properties of a good antibiotic.