On the battlefields of World War I, soldiers are dying from infected wounds. A young doctor witnessing the devastation vows to find a cure. In his messy laboratory a decade later, he makes an accidental discovery—a miracle mold that kills bacteria. But try as he might, he cannot turn his amazing find into a useful medicine.

This is the story of that chance discovery and the brilliant scientists who took Alexander Fleming’s miracle mold and worked tirelessly to turn it into a treatment that doctors could use. As another war broke out in Europe, they found themselves in a race against time to grow enough penicillin and create the first antibiotic. Their teamwork and determination led to a class of drugs that saved countless lives and paved the way for modern surgery and other life-saving treatments.