The paper describes the grammar of the detective genre. This is done on the basis of formalist-structuralist poetics, by extracting the actants of detective syntax. It involves: the plot, enigma, secret, solution, crime, and the detective. The plot is determined both on the basis of the main stages of the detective narrative (crime, investigation, explanation) and depending on the reader's reading experience. An enigma is the absence of information about someone/something, but it is also part of the plot - it hides events which led to a specific crime. The secret is connected with the enigma and concerns both the crime and the detective. The solution is considered by many to be the most important feature of the detective genre, which has a distinctly ideological character. A crime is a motive, not a goal - it happens outside the text, and is transmitted through the text. The detective is a distinctive figure of this genre, determined by intellectual and scientific abilities, but also by eccentricity and fragmentation.