"Admirable, superbly researched ... perhaps the most exciting tale of science since the apple dropped on Newton's head."--Simon Winchester, The New York Times. Alexander Fleming's discovery of penicillin in his London laboratory in 1928 and its eventual development as the first antibiotic by a team at Oxford University headed by Howard Florey and Ernst Chain in 1942 led to the introduction of the most important family of drugs of the twentieth century. Yet credit for penicillin is largely misplaced. Neither Fleming nor Florey and his associates ever made real money from their achievements; instead it was the American labs that won patents on penicillin's manufacture and drew royalties from its sale. Why this happened, why it took fourteen years to develop penicillin, and how it was finally done is a fascinating story of quirky individuals, missed opportunities, medical prejudice, brilliant science, shoestring research, wartime pressures, misplaced modesty, conflicts between mentors and their proteges, and the passage of medicine from one era to the next.