Roman Polanski directs like a man 65 years his junior (yes, that would make him 18), in his manic and ludicrous literary thriller Based on a True Story, co-written with Olivier Assayas and based on Delphine de Vigan’s novel.

Delphine (Emmanuelle Seigner) is a successful but unhappy author. After cutting short a book signing, she meets Eva Green’s Elle (short for Elizabeth, but altered in the English subtitles to Her and Hermione to maintain the poetry). Elle is fascinated by her work and Delphine is delighted to finally have someone she can really talk to. But Elle, a ghostwriter herself (seriously), begins to force her way into Delphine’s life, helping with her writing and answering emails. Meanwhile, anonymous letters keep showing up on Delphine’s doorstep attempting to blackmail her by exposing her last book as an exploitative co-opting of the truth.

The film plays like something of an erotic thriller; although, for all the sexual tension, Polanski avoids indulging in any bodily delights. It is very much a two-hander and, as the film progresses and tension builds, the ad hoc couple separate themselves more and more from the outside world.

In the vein of those genre films, identity and communication become key themes and fears. Polanski also plays with nightmare sequences to add a surreality to the melodrama. As with the best intimate thrillers, the film’s aided by a lovely score, courtesy of Alexandre Desplat. It’s used heavily but manages to avoid feeling overbearing thanks to Desplat’s light and lilting keys and strings.

Polanski and Assayas also take the chance to indulge in the exploration of writerly fears (that of the blank page and research woes, particularly). It’s hilariously petty and plays as such, but Polanski and Assayas at least seem half aware of that. This is just one example of the film staggering on the line between funny and laughable. For all the chuckles, Based on a True Story loses the plot a bit by the end and leaves things open for ridiculous debate.

Green has a lot of fun with the role and chews the scenery as if it’s a stale baguette. As with the rest of the film, her performance tips too far over into hysteria by the end, but Green makes for a fun crocodile to Delphine’s mouse. And murine-like Delphine certainly verges on wooden at times, but most actors would seem that way when playing against Green in full red-lipsticked, wild eyes mode.

But for Polanski to commit wholeheartedly to his female leads, at the expense of the minor male roles, is admirable. Although that doesn’t bypass the fact that Delphine is a clueless lead; she doesn’t understand Facebook, doesn’t reply to her emails and didn’t set her own laptop password, all of which service the plot nicely, in some form or another. That being said, Delphine manages to add some fight to the power struggle as she begins to challenge Elle’s dominance.

The title is, of course, a knowing joke. Based on a True Story couldn’t be further from reality. At one point, Elle declares that people believe the printed word. You certainly won’t believe the film adaptation, but that doesn’t mean there isn’t some fun to be had on the way.

Benedict Seal (@benedictseal) is a UK-based film journalist for the likes of Bloody Disgusting, VODzilla.co and New On Netflix.