Introduction. The article analyzes the novel “The Storyteller” written by the Peruvian writer Mario Vargas Llosa. The novel is characterized by two stylistically different parallel parts. The purpose of the study: to identify the stylistic difference between the two parts of the novel using one of the most reliable stylometric tools (Burrows’s Delta), and also to check whether this tool can calculate the difference not between the texts of fundamentally different authors, but between chapters written by one person. Methodology and sources . The key method is Burrows’s Delta, which allows comparing texts with each other based on the distribution of the most frequent vocabulary. The Zeta measure is also used, which serves as a means of identifying differentiating vocabulary in the chapters of the novel “The Storyteller”. Results and discussion . Three series of experiments were conducted. In the first series, parallel parts of the novel “The Storyteller” are placed in a corpus with the rest of Vargas Llosa's novels. As a result, the “European” part (chapters I, II, IV, VI, VIII) is classified by the algorithm as a documentary text, while the “Peruvian” part (chapters III, V, VII) is characterized by its proximity to total novels written in the 1960s. In the second series of experiments, it is tested whether the algorithm will detect differences between specific chapters that make up the two parts of the novel. As a result, the chapters are classified into different branches, and the algorithm has confirmed its reliability. The third series of experiments is devoted to identifying differentiating vocabulary using the Zeta measure. Several classes are identified that allow us to distinguish the “European” part from the “Peruvian” one. Conclusion. By means of the Burroughs Delta algorithm, the stylistic two-voice nature of Mario Vargas Llosa's novel “The Storyteller” is confirmed; moreover, it is shown that the algorithm itself is a sufficiently sensitive tool not only for recording the author's signals a priori of different writers, but also for characterizing the variability of one author's style.