在“上流社会”中,编剧兼导演尼达Manzoortells the story of two sisters living in a British Pakistani family. But she focuses her attention on the wrong sister.

In the process, she borrows from several different genres — family comedy, high school comedy, sci-fi satire and martial arts extravaganza — and fails at all of them.

Charm, of course, is in the eye of the beholder. Still, it’s hard to see by what measure of appeal could a poisonous, spiteful, neurotic and violence-prone younger sister be regarded as a protagonist anyone would want to watch for 100 minutes.

Ria (Priya Kansara) is a high school girl who dreams of being a stuntwoman, though her parents want her to become a doctor. Also living under the same roof is Lena (Ritu Arya), Priya’s poised older sister, who recently lost her confidence. She has returned home after dropping out of art school, and now she’s living an aimless existence, wondering what to do next.

Ria insists that her sister is a great artist and just needs to pick up her brushes and start painting again. But we don’t trust Ria’s assessment, because it takes about two minutes to establish that Ria knows nothing but is sure about everything.

Then one day, something good happens to Lena. She meets Salim (Akshay Khanna), who is good-looking, nice, a doctor, and was born rich. One could argue that Lena’s aimlessness has made her more susceptible to see any worthy suitor as a potential deus ex machina. Yet why shouldn’t she weigh this option when it’s presented to her? And how can we help seeing this new man as a positive thing in her life?

Of course, Ria hates Salim on sight and does everything she can to undermine Ria’s relationship with him. This is where “Polite Society” becomes frustrating. Instead of staying with Lena, an adult woman contemplating a future much different than the one she once imagined, the movie follows Ria, who is angry, grating and reckless and just wants to ruin things.

In her feature debut, Manzoor does something truly bizarre here, and not in a good way. She gets a whole audience rooting for love to triumph but then tries to make a lovable heroine out of the irrational, malevolent character who wants to undermine everything the audience is looking forward to.

As is not uncommon when filmmakers direct their own screenplay, Manzoor has a shaky command of tone. She assumes it all hangs together, perhaps because it hung together in her mind as she was writing it. But on the screen, we get something of a mess — emotional scenes meant to be taken seriously, along with characterizations that are borderline fantastic and violent martial arts scenes intended to be whimsical.

It’s quite possible that, in the future, in another role, Kansara will be an engaging screen presence. The problem isn’t Kansara, but the fact that Manzoor clearly wants us to regard her sympathetically. Well, Manzoor is insisting on the impossible. As Ria, Kansara is all too convincing at being awful.

The one thing to save from the wreckage of “Polite Society” is Arya, who, despite the constraints of a weak script and limited screen time, is able to suggest an intelligent woman trying to maintain a cool facade while experiencing a painful internal conflict. Arya, who was a welcome addition in seasons two and three of the Netflix series “The Umbrella Academy” and will be on the big screen this summer in Greta Gerwig’s “Barbie,” belongs in more movies — but better ones than this.

Reach Mick LaSalle: mlasalle@sfchronicle.com