In this universe, humanity is no longer Earth's superior race; they are nothing compared to the various species of supernatural creatures that have come to threaten their very existence. 

PURGE is a government-funded organization focused on the takedown of supernatural creatures that qualify as "threats to humanity"--namely, the dangerous ones. 

It is generally believed that humanity's faith lies in PURGE, but unfortunately, their faith actually lies in a childish and underweight assassin.