In a small French village, the quiet and somewhat clumsy Monsieur Leguignon leads a monotonous life as a plumber, a job that keeps him away from action and excitement. Everything changes abruptly when a mysterious murder shakes the community. The atmosphere of peace is disrupted, unleashing a series of suspicions and rumors that sow distrust among the inhabitants.
As the entire village turns into a sea of speculation and outrageous theories, Leguignon, driven by his curiosity and an unusual perseverance, is drawn into the investigation of the crime. Although he is a common and simple man, his wit and ability to observe details lead him down an unexpectedly daring path. In his quest for the truth, he encounters peculiar characters who, with their own secrets and eccentricities, help (or hinder) him in his inquiries.
Little by little, Leguignon begins to unearth clues that prompt him to rethink everything he thought he knew about his surroundings. With a comedic tone and an almost absurd escapade at every turn, this story shows us how an apparently mundane man can become an improvised hero. In the end, he not only hopes to solve the murder mystery but also to discover a little more about himself, reminding us that often the true mystery is closer than we imagine.