Perfume critic and collector, Turin Luca, a Biophysicist at University College London, has proposed a new theory about how we smell. His theory might have a powerful impact on the medical profession. He travels to Paris to meet perfumer and chemist Maurice Roucel who breaks fragrances down to their individual molecules. What gives a molecule its odour is, as yet, unknown. Chemist Charles Cell describes why it is so difficult to read the molecular structure of smells. Luca's new theory followed on from the research of John Amoore who discovered that most people can't smell at least one odour. He realised that this was due to the fact that receptors were missing inside the nose, meaning that they couldn't detect the shape of certain molecules. But Luca's research took this further and he started to study smell as being related to vibrations, that the nose detects vibrations.