In a country infamous for its drug cartels, Mexico has another booming black market - petrol. Starting out as just a few individuals tapping lines to sell to their local communities, petrol theft has now attracted the heavyweights of organised crime who see the appeal in peddling a product that is used by more of the population, and that does not even need to cross a border to be sold. Yet, as the government and gas company Pemex race to find a way to stop the fuel thieves, known throughout Mexico as huachicoleros, there is more evolving than confrontation.