Despite the swear word in the title, Netflix's new show Don't F*** With Cats sounds relatively benign — as if it is tapping into the internet's obsession with funny cat videos.

But it's much darker than that.

Warning: This story contains graphic details which may disturb some readers.

A grainy picture released by the Montreal Police during the search for Luka Magnotta. ( Reuters: Montreal Police )

Don't F*** with Cats: Hunting an Internet Killer is a true crime documentary about social media sleuths attempting to track down a man who posted a video of himself killing two kittens and playing with their bodies.

That mysterious man, Luka Magnotta, went on to murder and dismember 33-year-old Chinese computer science student Lin Jun, posting footage of the killing on the internet.

The high-profile case, which came to a head in 2012, was global news.

So rather than recapping Magnotta's horrific crimes, Netflix focuses on the social media detectives and their game of cat and mouse with a killer.

This internet manhunt started with the first video in 2010.

"You can post porn, violence, somebody getting pushed down stairs, religious statues being defamed… and nobody gives a crap," says Deanna Thompson, one of the internet sleuths,

"But in this seedy underbelly, there's an unwritten rule. And rule zero is 'don't f*** with cats'."

Ms Thompson and John Green talk viewers through their initial horror at the footage and how they narrowed in on tiny details to track Magnotta down.

The killer taunted internet vigilantes by dropping confusing digital breadcrumbs and posting more sickening videos.

Eventually the torture videos escalated to murder.

You don't actually see the videos, do you?

Netflix tweeted that the series was "tough to watch", and listed it as "adult" content, but that was not enough of a warning for some viewers.

The series references disturbing videos Magnotta created, taking some viewers off guard.

In one of the videos Magnotta suffocates two kittens in a plastic bag. In another, he feeds kittens to a snake.

While the videos aren't shown in their entirety, viewers took to social media to warn others that snippets of the footage and audio do feature in the series — including a short amount of footage from the clip of Mr Lin's murder.

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For many, that made for uncomfortable and distressing viewing.

"Even though it wasn't the actual torturing/murdering it made me sick to see even parts of it," one Redditor wrote in a forum about the show.

"Although they cut away before anything truly horrifying happens, the images shown are incredibly disturbing for me," another said.

Some compiled a list of timestamps detailing the most upsetting moments in the series for those wanting to skip over the distressing scenes.

Is this just feeding the killer's desire for attention?

That's something many viewers were left contemplating after watching the show.

"I can't help but picture Luka smiling ear to ear knowing we gave him a whole docuseries on him… this is exactly what he wanted," one viewer wrote on Twitter.

WARNING: Spoiler below

In a review for British news site inews, Emily Baker wrote about the guilt she felt for watching the series, particularly after the last few minutes of the final episode.

"It's also a comment on our society's obsession with crime and the unintentional idolisation of murderers," she wrote.

"Thanks to this film, I don't know if I will ever be able to watch a truly gripping true crime documentary again."

Ms Thompson, one of the social media detectives, questions whether tracking down Magnotta fed his narcissism and contributed to his crimes.

But she goes further, questioning the very ethics of the documentary itself.

"You at home watching a whole f***ing documentary about Luka Magnotta," she says, speaking to the camera. "Are you complicit?"

This pointed question left many feeling uncomfortable.

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How gruesome is the story?

The crimes Magnotta committed are extremely disturbing.

So if reading about gory murder details upsets you, prepare yourself for some heavy content or make a decision about whether to continue on.

Magnotta killed Mr Lin in 2012, stabbing him repeatedly with an ice pick and cutting up his body. The murder featured in a 10-minute video, in which Magnotta goes on to desecrate Mr Lin's body.

Police said he ate part of the body, and sent the student's hands and feet to Canadian political parties and schools.

Reports from Reuters said the parts were mailed in packages with pink paper and hand-drawn hearts.

Mr Lin's severed torso was found in a suitcase discarded in a pile of rubbish.

Pink tissue paper submitted as evidence at Magnotta's trial. ( Reuters: Montreal Police )

Canadian authorities began searching for him after the grisly discoveries were made in May 2012, but Magnotta fled the country.

A global manhunt ensued, with the media dubbing him "Canadian Psycho".

What happened to the killer?

Magnotta was eventually arrested on June 4, 2012 in an internet cafe in Berlin, where he was reading news stories about himself.

He was extradited back to Canada on a Canadian Royal Air Force plane about two weeks later.

Magnotta was dragged back to Canada after being arrested in Europe. ( Reuters: Service de Police de la Ville de Montreal )

Magnotta denied the charges against him and went to trial in September 2014.

His legal team admitted Magnotta killed Mr Lim, but claimed he was not criminally responsible at the time of the killing because of mental illness.

After eight days of deliberations, a jury found Magnotta guilty of first-degree murder.

Magnotta was also found guilty of committing an indignity to a human body, publishing and mailing obscene material, and criminally harassing then-Canadian prime minister Stephen Harper and other members of Parliament.

A first-degree murder conviction in Canada carries an automatic life sentence with no possibility of parole for 25 years.

Magnotta remains behind bars, with the Montreal Gazette reporting he married a fellow inmate in June 2017.

Magnotta was eventually found guilty on five charges, including committing an indignity to a human body. ( Reuters: Atalante )

ABC/Reuters