It has 16-year-old Jesse (a haunted-looking and effective Fanning) newly arrived in Los Angeles hoping her only talent - being pretty - will land her something.
She gets an agent (Christina Hendricks), who advises her to up her age, and a new friend, makeup artist Ruby (Jena Malone).
Through Ruby, she meets a couple of established models (Abbey Lee and Bella Heathcote), who scowl with surgically enhanced pouts at their young competition. Jesse becomes the new It-Girl with her deer-in-the-headlights thing.
However, she also has to deal with a clingy boyfriend, a menacing landlord (Keanu Reeves) and the aforementioned mountain lion, which turns up in her scuzzy motel room as possibly a metaphor for ... something.
(One theory: maybe the script for this sexually free-wheeling film by Refn and playwrights Mary Laws and Polly Stenham called for a "cougar' only to get lost in the translation).
So, anyway, shock horror: modelling is an ugly business and only young, worryingly thin people need apply.
But you wouldn't want to take The Neon Demon as serious commentary on the superficiality of beauty or the glamour business, even if Refn has styled ads for the likes of Gucci.
It's more an outlandish art-trash horror film.
One that makes David Lynch's Mulholland Drive, which it sometimes resembles, feel like a work of narrative clarity and breakneck pace by comparison.
Having got Jesse to the point of next-big-thingdom, the second half largely abandons its story becomes a lookbook of shock shots.
That includes a spot of Sapphic necrophilia (clearly also possibly a metaphor for ... something), and mass model audition, which looks more slave market.
And there is some grim business in a Hollywood Hills mansion involving the place's swimming pool that is definitely a metaphor for the whole movie: It's luxurious. It looks deep. But it's drained and empty.
Verdict:The catwalk to hell
Cast: Elle Fanning, Christina Hendricks, Keanu Reeves, Jena Malone, Abbey Lee, Bella Heathcote
Director: Nicholas Winding Refn
Rating: R18 (Violence, horror, sexual material & necrophilia) Running time: 118 mins