Adrien had a nosy girlfriend named Nora, a professional woman who's understandably frustrated by his lack of activity and who decides to take a sneak peek at his computer, that's strangely not password locked
Regardless of Nora's ease of access to Adrien's PC, the result of her action is to enrage Adrien, who wants to keep his writing private, also because he's probably planning to make it pass as the result of his own imagination, rather than the real story of a couple named Albert and Solange.
In the sunny 70s the murderous couple gets to action, with Solange working as an "allumeuse", also known as tease in English, so that Albert can kill whomever takes her "offer" seriously and the two of them can enjoy wild sex after the kill. Because everybody knows that sex is so much better after you kill someone...
We get it, murder excite them, no need to see them copulating covered in blood... but still a powerful episode.
PS do not forget the policeman in the background.