Although academic work on conspiracy theory has taken off in the last two decades, both in other disciplines as well as in epistemology, the similarities between global sceptical scenarios and global conspiracy theories have not been the focus of attention. The main reason for this lacuna probably stems from the fact that most philosophers take radical scepticism very seriously, while, for the most part, regarding ‘conspiracy thinking’ as epistemically defective. Defenders of conspiracy theory, on the other hand, tend not to be that interested in undermining radical scepticism, since their primary goal is to save conspiracy theories from the charges of irrationality. In this paper, I argue that radical sceptical scenarios and global conspiracy theories exhibit importantly similar features, which raises a serious dilemma for the ‘orthodox’ view that holds that while we must respond to radical scepticism, global conspiracy theories can just be dismissed. For, if, as I will show, both scenarios can be seen to be epistemically on a par, then either radical sceptical scenarios are as irrational as global conspiracy theories or neither type of scenario is intrinsically irrational. I argue for the first option by introducing a distinction between ‘local’ and ‘global’ sceptical scenarios and showing how this distinction maps onto contemporary debates concerning how best to understand the notion of a ‘conspiracy theory’. I demonstrate that, just as in the case of scepticism, ‘local’ conspiracies are, at least in principle, detectable and, hence, epistemically unproblematic, while global conspiracy theories, like radical scepticism, are essentially invulnerable to any potential counterevidence. This renders them theoretically vacuous and idle, as everything and nothing is compatible with what these ‘theories’ assert. I also show that radical sceptical scenarios and global conspiracy theories face the self-undermining problem: As soon as global unreliability is posited, the ensuing radical doubt swallows its children – the coherence of the sceptic’s proposal or the conspiracy theorist’s preferred conspiracy. I conclude that radical sceptical scenarios and global conspiracy theories are indeed partners in crime and should, therefore, be regarded as equally dubious.