Unreliable narration by definition involves deformation of the represented world. The narrator tells the story in the manner that makes the reader suspect that he / she is perverting the facts, manipulating the data, omitting details or simply lying. The narrative situation of this type can be observed in Tanguy Viel’s debut novel Le Black Note, published by the prestigious Minuit publishing house. The aim of this essay is to analyse unreliable narration as a modality of deformed representation of reality and to assess its impact on the reading process. This typically destabilising narrative technique reflects the condition of the deranged mind and thus depicts the distorted view of reality filtered through diseased consciousness. Subverting the traditional author–reader pact as well as the narrator’s authority, it constitutes one of the narrative paradigms typical of contemporary fiction.