If you haven’t seen it, imagine Airplane! or The Naked Gun but made by French comedians who hate pretentious cinema. That’s Cité de la peur .
They travel from Cannes to Paris, chasing clues that make no sense. The killer (still in the diving mask, still carrying a baguette) keeps striking. He kills a projectionist by forcing him to watch a bad film. He kills a script supervisor by… giving her a bad review. Eventually, after many nonsensical chase scenes (including one where they run through a museum and discuss existentialism while being chased by a mime), Simon has an epiphany: the killer is copying the murders from Red Is Dead . But since Red Is Dead is a fictional film, the only person who could know the script is… cite de la peur
The killer is (played by the director of the real film, Alain Berberian, in a cameo). Why? Because the director was furious that Serge had rewritten his script, turning his serious psychological thriller into a stupid horror-comedy. So, he decided to literally kill the film by murdering people in the most ridiculous way possible—with a baguette—to make the whole project a laughingstock. If you haven’t seen it, imagine Airplane
Simon accuses Serge. Serge, flustered, admits he wrote the script. But then Serge accuses Agnès. Agnès accuses the caterer. It’s a mess. Finally, through a series of absurd deductions (including a clue about a rare type of breadcrumb found at every crime scene), Simon realizes the truth. They travel from Cannes to Paris, chasing clues
Simon, despite being a complete failure as a detective, gets the girl. He and Agnès kiss while a subtitle on screen reads: "They lived happily ever after. Until the sequel."
It’s not a “long story” in the literary sense (like a novel), but rather a parody of crime thrillers and film industry tropes. However, I can tell you the as a long, detailed narrative.