It is argued that the legitimacy of an emergent technology, such as nanotechnology, depends on its ability to develop a narrative that mobilises and integrates a number of pre-existing narrative scripts. In the case of nanotechnology, especially in its NBIC variant (i.e. the convergence of Nano, Bio, Information technology and the Cognitive sciences), the narrative types include science as transcendence, risk, hype, social accountability, ELSI (Ethical Legal and Social Implications) and Science Fiction. This article draws on a number science studies fields to show how components from each of these narrative types make their appearance in the discourse of nanotechnology, but also how they are ordered and stabilised around a key metaphor: practitioners of nanotechnology as master builders. This metaphor links nanotechnology to Science Fiction as a key site for the construction of alternative worlds, and also to the above-mentioned narrative scripts. In the conclusion, some troubling implications of how nanotechnology is currently legitimated are highlighted.