Los Olvidados (1950)

Hell-bent on revenge, cocky reform-school runaway El Jaibo returns to his old neighborhood in post-World-War-II Mexico City's poor and squalid slums, to reunite with his faithful gang of juvenile delinquents and street urchins. However, as the dangerous ringleader lives and breathes retribution, his destructive obsession to find the informant who supposedly sent him to jail will intricately interweave his bitter fate with that of Pedro, his weak, unwitting accessory, in a despicable act of pure evil. In the end, are humans inherently good or bad? Is immorality contingent with society?