After revealing nanosciences in the previous episodes, we now look at the passionate debates they have caused in the scientific and political spheres. Although this nanoworld may sometimes resemble science-fiction, its first practical applications and social implications, its economical and public health aspects all trigger an animated debate over progress, science, and the future of mankind and the planet. What are the consequences of the emergence of nanotechnologies? What are the risks? Institutions and NGOs take part in the debate. Research and manufacturing laboratories, along with places concentrating nano promoters, including opponents’ protests, are all the protagonists who help us blaze a trail between fantasy and reality.