Abstract Prebunking can be used to pre‐emptively refute conspiracy narratives. We developed a new approach to prebunking – fighting fire with fire – which introduces a plausible ‘meta‐conspiracy’ suggesting that conspiracy theories are deliberately spread as part of a wider conspiracy. In two preregistered intervention studies, prebunking specific COVID‐19 vaccine (Study 1, N = 720) and climate change (Study 2, N = 1077) conspiracy theories (e.g. that climate change is a hoax), with or without this meta‐conspiracy framing, did not reduce beliefs in these specific conspiracy theories. However, some notable findings emerged. First, both fighting fire with fire and standard prebunking (Study 2) increased belief in plausible meta‐conspiracies that questioned the original specific conspiracy theories. Second, across both studies, specific conspiracy beliefs negatively predicted behavioural intentions, while beliefs in meta‐conspiracies positively predicted them. Third, specific conspiracy beliefs were negatively related to belief in plausible meta‐conspiracies in both intervention studies (cf: Pilot Study). While this approach did not reduce specific conspiracy beliefs, it increased beliefs that were negatively associated with them and which were positively linked to behavioural intentions. We discuss these null effects and their implications for effective prebunking among conspiracy believers.