“Operation Mayfair” is an Indian serial killer thriller set in London, a film meant, no doubt, for domestic consumption on the Subcontinent and never really intended for prying, judging, non-Hindi-speaking eyes and ears.

It’s dreadful by most any measure — violent, tin-eared, clumsily-staged and uncertainly-acted. And it’s head-slappingly stupid as a police procedural. Honestly, I think all the “research” the screenwriters did was watch old serial killer episodes of 1970s TV.

But there are times it is amusingly quaint in conception and execution, a film in English with generous helpings of Hindi that has the great Indian diaspora in British policing take over a high profile mass-murderer-on-the-loose case, with the bloody butcher also one of the British investigators of Indian descent.

The film opens with a murder straight out of a ’70s porno — a hooded killer slips into the unlocked home of a model, takes her hostage, paints “black teardrops” (think Tammy Faye Baker after a crying jag) on her face, whips her to score her back, snaps her neck and lops off a finger.

All the time, he’s raving, flashing back to some unpleasantness from his youth, letting us see the stepmom (we learn) who abused him and called him a “MORON!” so many years before create this monster.

The nature of the crime, the “pose” of the victims, means there’s a previous Mayfair murderer back in business. Or a copy cat. Detective Chief Inspector Lisa Varma (Vedieka Dutt) begs her boss (Bryan Lawrence) to “bring back Det. Amar,” who failed to crack the first case and now teaches architecture at Oxford.

Sure. That scans.

Veteran Sikh actor Jimmy Shergill (Indian TV’s “Your Honor”) plays Amar, a sleuth who can read a crime scene or a crime scene photo for clues like no one else, although we see little evidence of this. Again, he had one crack at this supposedly dormant killer who has become “active” again. Perhaps Amar, with a wife and child at home, was distracted. You know, by the subordinate cop Sonya (Hritiqa Chheber) he was having an affair with.

Now that he’s abandoned academia (!?) to return to the case, he’ll need lots of chaste, non-case-related meetings with Detective Constable Sonya just to reminisce over their affair. Apparently.

That’s a shame, because he needs to focus on the case. And as we’ve seen who the killer is in the opening scenes, we know he’s the FORENSICS expert (Ankur Bhatia) assigned to the “operation” task force. Catching this guy will take a Sikh/British Columbo.

“I think the killer is doing all this to deviate our attention,” Amar suggests. “This is a MURDER case, not some petty pickpocket stuff!” he rages.

“”I’m sorry sir, but if I’m not allowed to flex my muscles, then what is the use of bringing me down over here?” he complains.

The picture’s never quite what one would call incompetent, just off in ways anybody who’s ever seen a serial killer thriller or a movie set in London will recognize.

An assignation scene uses what looks like a storefront to pass for a cafe, with an outdoor table and the inclusion of a paper Union Jack in the window the only decor the budget would allow.

Bhatia renders every murder lurid with silent cinema-styled eye-bugging, eye-rolling hysterics. Every “clue” seems invented, every argument or obstacle contrived, every interlude with the lovely Sonya a tease.

A multi-cultural society like Britain should certainly portray a police force with senior, accomplished Sikh, Pakistani and Hindi cops. But running off to teach architecture at Oxford after a falling out over a case, “joining” an investigation without being hired or sworn back into the force, quibbling over working for “my former” junior colleague, there have to be more graceful ways of introducing characters, more believable plot points and an effort made to avoid laughable “plainly an out of town production” blunders.

What a debacle.

Rating: TV-MA, graphic violence, suggestion of sex crimes

Cast: Jimmy Shergill, Vedieka Dutt, Hritiqa Chheber, Bryan Lawrence and Ankur Bhatia

Credits: Directed by Sudipto Sarkar, scripted by Anthony Khatchaturian and Sudipto Sarkar. A Netflix release.

Running time: 1:55