Peaky Blinders has earned itself a cult following since hitting BBC Two four years ago.
So much so that the show's star, Cillian Murphy, has seen pictures of fans with giant tattoos of his character Tommy Shelby (yes, really).
In the past three series of the gangster epic, set in post-First World War Birmingham, we've seen Tommy move up in the world as the brains behind the most feared and powerful gang in the area, the Peaky Blinders.
Run by him and his family, they make money from illegal betting, protection and the black market - while also making plenty of enemies along the way.
Ahead of the show's return, Murphy and co-stars Helen McCrory and Adrien Brody tell us about the danger awaiting the Shelby family this time round.
Murphy returns for another striking performance as flat cap-wearing, chain-smoking gang boss Tommy.
Series three ended with viewers wondering what Tommy was playing at by turning four members of his family - his Aunt Polly, his brothers Arthur and John, and cousin Michael - in to the police.
He's always been the linchpin but now it's business first and family second - or so it seems, as he remains unforgiven and estranged from the rest of the Shelby gang.
"I don't know if he is willing to walk, I think he's really trying not to think about it, and he's just getting on with it," reveals 41-year-old Murphy, who has also starred in huge films such as Dunkirk this year.
"He's a really, really, really complicated man emotionally, he doesn't deal with stuff ... He loses his wife in series three and I think that any progress that he'd made emotionally through being married and through her, he's gone back."
Tommy redeems himself in some of his relatives' eyes early on in series four by coming to the rescue of incarcerated family members, but Irish actor Murphy hints that the Shelby relationships are still "complicated and messed up".
Tensions rise when Tommy receives a letter on Christmas Eve with a Black-Hand - a mark of a warning from the Mafia - and the family's only option could be to reunite in Small Heath (the slum where Tommy grew up).
"The idea was to put them under the greatest threat that they've ever been (under) really," explains Murphy.
The source of the threat is mobster Luca Changretta, played by Brody, who is seeking revenge over an assassination in series three.
Of Brody, Murphy says: "He just has incredible energy, which we'll get to see as the show progresses; obviously it's going to be a showdown at some point."
Skyfall and Harry Potter star McCrory plays matriarch Aunt Polly, who fiercely ran the Peaky Blinders while the men were in the trenches of the First World War, and long ago made peace with the family's criminal activities.
But following nephew Tommy's betrayal - which led to her imprisonment - Polly is a broken woman, and has to ask herself if she can forgive him for the sake of her family's future.
Especially because early on in the first episode, we see Polly face the terror of being led to the gallows - a scene that McCrory, who has also worked extensively on stage, found challenging to film.
"It's very disturbing," the 49-year-old actress elaborates. "Because we are all mortal, and we're not a culture that really talks about it."
The experience is a real turning point for Polly as a character.
"We see her believing that she's going to die," McCrory explains."She calls on the Virgin Mary to bring the spirits of her mum, her dad and her daughter to her. In that moment, she believes she sees her daughter's face and from this moment on, Polly believes that she's living with the spirits constantly around her."
This, McCrory explains, leads to Polly no longer being scared of death. Will this newfound attitude come in handy when fighting the Peaky Blinders' enemies this series?
"She's an equal because of her lack of fear of death," affirms London-born McCrory, who is married to Homeland star Damian Lewis.
"She (Polly) now no longer refers to anybody in order to act, and that's what has changed.
"She now makes her own decisions and that makes her really dangerous."
So, whether we will see a long-term reunion between Polly and her nephew Tommy, who she has looked after since he was young, remains to be seen.
"She (Polly) hates the man that runs the family (Tommy), even though she is a matriarch, and he is the patriarch and therefore, will they have to reunite in order to run the family? Will she unite or will she take him down?" teases McCrory.
Peaky Blinders has attracted actors of huge calibre in the past, and this series is no disappointment, what with the addition of award-winning American actor Brody to the cast.
The 44-year-old portrays Luca Changretta, a formidable gang leader who has recently been released from prison and arrives in the UK from New York fuelled with hatred.
Brody actually grew up in New York City himself, and it seems being aware of the gang culture in his local neighbourhood of Queens has influenced his work.
"I knew many people who were affiliated and associated with both unorganised and organised criminal enterprises," he elaborates.
"It's a part of growing up in New York City, there was a large Italian-American community within the neighbourhood ... It's just par for the course.
"It's wonderful ammunition now that I'm an actor, because I have many experiences and truths to draw from that you might think are far-fetched to be in a film. I find it remarkable what there is to draw from and I'm grateful for that."
When it comes to the Peaky Blinders encountering Luca, Brody, who won an Oscar for his role in Roman Polanski's The Pianist in 2002, thinks it will be "intriguing" to see how viewers empathise with the new mobster.
"You're going into a story where I would say almost everybody is rooting for the Peaky gang and here is an outsider from another world, and that's exciting, that's alluring to me," he maintains.
Of his dangerous and complex character, Brody adds: "He's a family man and he's a man with integrity, and he may not operate on a level that is appropriate within society, but on some level there is a real love and respect for family; not only his own, but others'."
In what ways has Tommy met his match in Luca?
"They're both extremely driven, family orientated and intelligent, in a way that goes beyond boundaries," Brody responds. "That's a lot of fuel for any encounter between the two of them, because with that comes respect and admiration and a degree of trepidation, because you're dealing with someone that you know has the potential to do what you have the potential of doing.
"And once you start playing in those terms, you're cooking with gas."
Peaky Blinders returns to BBC Two on Wednesday, November 15 at 9pm.
Don't miss an episode with BT TV - catch up via the BBC iPlayer app.