Climate denialism has been understood, particularly by the vast majority of the scientific community and by environmentalist political actors as a mere manifestation of ignorance on the part of parts of the population. Who did not have access to knowledge? However, by acting diffusely and almost always in a typically hidden way (that is, difficult to see by the “common man,” that is, by most of the population), the lobbyists and public opinion makers who conveyed the denialist discourse on climate change have, so far, been able to enjoy broad freedom to act by disseminating their speech to the general population. Thus, this type of propagandist activity often has a similar (or even greater) space in the media than that given, for example, to scientists. In this context, in a typically critical dialogue with climate denialism, the documentary film “The campaign against the climate”, released in 2020, brings the associated financing means out of the shadows. Particularly, the role of the fossil fuel lobby is analysed in detail. Through comparative analyses and in-depth systemic bibliographic review and extensive digressions focused on the documentary in question, it aims to establish and analyse the interrelationships between the hidden strategies of this industry and climate change mitigation. It was possible to infer, as a result, how complex and challenging it has been, even in the context of multilateral negotiations led by the United Nations, to overcome the obstacles established by the Big Oil’s lobbying activity and, finally, mitigate climate change