Discover Isaac Newton's lesser-known but fascinating second career as Master of the Royal Mint. In this episode, Dr Sarah Quinn explores how the legendary physicist became England's most effective counterfeiter hunter, transforming from theoretical scientist to practical crime fighter. Learn about Newton's role in the Great Recoinage of the 1690s, his detective work in London's underworld, and his legendary pursuit of the notorious counterfeiter William Chaloner. We examine how Newton applied his scientific methodology to financial crime investigation, introducing revolutionary anti-counterfeiting measures and forensic techniques. The episode reveals how Newton's background in alchemy and metallurgy proved invaluable in identifying sophisticated fakes, and how his administrative skills transformed the efficiency of the Royal Mint. Discover the surprising ways Newton's work at the Mint influenced monetary policy for generations and provided him with the financial security to continue his scientific research. This compelling story demonstrates how Newton's analytical genius extended far beyond physics and mathematics, showing his remarkable ability to apply scientific thinking to solve practical, real-world challenges in 17th-century England.