Edmond Locard's L'enquête criminelle et les méthodes scientifiques marks a pivotal moment in criminology's transformation from a largely unmethodical practice to a scientific discipline. While Locard is best known for advancing laboratory methods of forensic analysis, this article argues that at the heart of his conception of forensics lies the assertion that it is not rationality, but vivid imagination that makes or breaks the criminal investigation. Following Locard's claim that one of the most crucial challenges in teaching forensics is to introduce fellow criminologists to the art of using intuition and creativity for problem-solving, this article examines the concrete ways in which L'enquête criminelle attempts to actively engage the reader's imaginative faculty by presenting problems that can only be solved through “lateral thinking” and “abductive reasoning.” To introduce his speculative methods, I argue, Locard borrows from detective fiction in two ways: Firstly, he counterfactually presents literary case studies by Poe as real-world cases, endorsing Dupin's detective technique as a viable criminological practice. By planting hidden clues and red herrings in semiotic puzzles to be deciphered by the reader, secondly, Locard appropriates narrative techniques to sharpen his reader's hermeneutics instincts.