Traditionally in Film Studies, the idea of cinema being able to put the truth on screen has been associated with one particular film theorist, namely André Bazin. However, only 6% of Bazin’s almost 2600 articles has been republished in anthologies or edited essay collections and reading the remaining 94% of these writings (which to date basically remains widely unread) makes it clear that Bazin was not so naïve. This paper focuses on an essay from 1947, one of Bazin's first and most important, "Tout film est un documentaire social" ["Every Film is a Social Documentary"]. It suggests that fiction films can tell the truth, but mainly in the way that dreams do, by revealing what people really think, or their collective unconsciousness, regardless of their conscious awareness. What is this truth which is told by any fiction film? How can one reconcile this theoretical perspective with Bazinian ontological theory of cinema in general? This article seeks to answer these questions by means of an in-depth analysis of that essay and of a wide range of examples taken from other, mostly unknown writings by Bazin.