In late 1982, the Mexican government responded to their country's financial crisis by centralizing their banks and devaluing the Peso, creating the Nuevo Peso in the process. (This much is at least true.)
And now for game world...
The Mexican people responded poorly to these changes, resulting in apathetic security and creative accounting at the new Banco de Mexico.
Once news of this spread to the US, some of the alternatively principled people in the Land of Opportunity looked south of the border for their ventures.
Players send their characters into Mexico with the intent of robbing the Banco de Mexico. They will need to acquire vehicles, seed money, weapons and perhaps some inside information to get the job done.
Multiple heists will be necessary to complete the target of 100,000,000 Nuevo Pesos. (Rough equivalent - one million US dollars.)