Why don't they want you to see it?

In the 1940s, a small Mexican town has seen its last three mayors assassinated in rapid succession. A naive janitor is recruited to become the new mayor, and he believes he will modernize the little town and usher in a reign of peace. But the system corrupts him very quickly, and he takes to abusing his power while associating with an unscrupulous assortment of opportunists, hypocrites and criminals.