Lava Jato, an unprecedented transnational corruption investigation that started in Brazil in 2014 and spread throughout Latin America, paralyzed economies, upended elections, and collapsed governments. What made ‘the largest bribery case in history’ possible in a part of the world where impunity for grand corruption is the norm? Why did it expand beyond Brazil and why did prosecutors prove effective in some countries but not in others? To answer this question, we trace the legacy of reforms that enhanced prosecutors’ structural capacity to combat white-collar crime. We also show that Lava Jato only became a full-blown anti-corruption crusade where reforms were coupled with investigators’ tactical decision to operate under the umbrella of taskforces that catalysed legal innovation and aggressive fact-finding. For some, the aggressive and unconventional methods deployed to uncover grand corruption were necessary and perfectly justified. Others saw dangerous affronts to the rule of law and democracy. Given these controversies, we also ask: How did voters in contexts with different levels of partisan polarization and aversion to politicians react to a once-in-a-generation attempt to clean politics? Did they instinctively back anti-corruption or did this zealous and unorthodox form of anti-corruption prove too difficult to support despite the long-standing yearning for a different kind of politics? Are anti-corruption crusades like Lava Jato capable of building strong and durable anti-corruption coalitions, or do anti-corruption methods sooner or later become fatally contested?