What makes knowledge dangerous? How does secrecy operate to help produce knowledge that is dangerous or otherwise? What happens when 'nothing happens'? This paper addresses these questions through a case study in the history of chemical weapons research in the UK. It focuses on the publication and subsequent treatment in 1975 of a newspaper article reporting that the patent on the chemical warfare agent, VX, was available in a number of public libraries. Within 10 days, copies of the patent had been withdrawn, a government review of declassification procedures was announced, and in Parliament the Minister for Defence announced that the Government had never patented VX. The implication was that nothing, or nothing worth worrying about, had happened. This paper draws on recently declassified documents to trace the modifications of position that occurred in order for the Minister to arrive at this announcement. I argue that secrecy enabled different readings of the patent in different places and thus acted as a spatial-epistemic tool in the exercise of power. Key features that differed were: the relationship between essential properties attributed to VX and the additional tacit knowledge deemed necessary to make the nerve agent; the degree of revelation that was deemed to have occurred as the secret was differently constructed; and the presumed intent and abilities of putative abusers. The paper closes with a brief consideration of the relevance of a science studies analysis of this case study to contemporary security concerns. © SSS and SAGE Publications.