HIS no-nonsense strategy of using any means required to capture criminals has dragged him down a perilous rabbit hole.
After five seasons on TV, the BBC psychological crime thriller series, Luther, continues the story of Detective John Luther in a new movie on Netflix.
His situation? Even darker and dire, of course.
In Luther: The Fallen Sun, British actor Idris Elba returns as the titular down-on-his-luck hero, who viewers first saw in 2010.
The charismatic artiste says that playing the complex character has been a gift.
"I think he's really observant and obsessed with his work. He's a good guy in bad circumstances who's trying to do good.
"I just love that landscape. He's complex. There are inner demons in John Luther that he hasn't quite faced. There are turmoil and grief, and he's lost people he loved.
"These are all ingredients that, as an actor, really pulled me across the spectrum of emotions, and I love that. It's been a gift," Elba says in a virtual chat from New York.
Directed by Jamie Payne and written by Luther creator Neil Cross, The Fallen Sun also stars English actor and director Andy Serkis as the cunning antagonist, David Robey.
On the wealthy psychopathic serial killer, Serkis says, "David Robey, to a certain extent, reflects humanity and the desensitisation that we've allowed ourselves to fall into by watching extremely violent images onscreen, not just on the Internet but also on the news at night.
"We watch very dark material as a part of everyday life, and we don't think about it.
"He is a psychopath and does shame people by using technology, but at the same time, he's on a mission.
"And anyone with the kind of ideology that David Robey has doesn't believe what he's doing is wrong because he wants to illuminate for society the ills that it has brought on itself."
Robey, who uses surveillance technology to manipulate and kill civilians, taunts the now disgraced and imprisoned Luther.
The valiant detective will have to take matters into his own hands again by escaping and putting an end to Robey's reign of terror in London.
Serkis adds that to play the character, he initially wanted to investigate the dark web, but then realised that "it was really a dangerous place to go".
"You don't know what's going to come back at you."
He also almost didn't want to take on the role after first reading the script.
"I felt that this was a very dark character, and it was very uncomfortable. But then I thought, 'No, it's my job as an actor to investigate it because it opens up a number of questions.'
"That was what I loved about playing the role because it opened up a debate about technology and our addiction to it."
As for Luther, Elba hints that there's certainly more gas in the tank for the downtrodden detective.
"He's really hitting rock bottom, but at the end of this, there's an opportunity for him to go in a different direction, maybe.
"And I'm excited about that direction since it will give us the opportunity for more films, more storytelling and perhaps a different type of work," he says with a smile.
Watch the latest exploits of Luther in The Fallen Sun at www.netflix.com/LutherTheFallenSun.