The new season of “Peaky Blinders” opens with the 1929 stock market crash — an apt metaphor for Tommy Shelby’s (Cillian Murphy) fractured British crime family.

“We meet the Shelbys just when they realize they’ve lost a huge fortune,” says Murphy of Friday’s Season 5 premiere. (The series is back on Netflix after nearly two years.) “This whole season is predicated on Tommy trying to keep the family together,” Murphy says. “He’s put under a lot of pressure by the family as a collective unit, with people pulling and pushing in different directions and he’s really feeling that.

“I think the younger generation in the family, embodied primarily by Michael (Finn Cole), is really making their presence felt.”

Tommy sent Michael (his nephew) to America in the Season 4 finale to expand the family business there — and it’s Michael, partying in Detroit, who alerts Tommy of the “Black Friday” market crash, setting in motion this season’s cascading chain of events with returning cast members Paul Anderson (Arthur), Helen McCrory (Polly), Sophie Rundle (Ada), Kate Phillips (Linda), Harry Kirton (Finn) and Aidan Gillen (Aberama Gold).

Tommy, meanwhile, is juggling his newfound position of power in Parliament with the rise of fascism in Britain, embodied by his political colleague Oswald Mosley (Sam Claflin). “I think Tommy is coming to grips with what his purpose is — what do you do and who do you do it for? — and he’s also achieved everything he possibly can, materially,” Murphy says. “In terms of power he’s at the apotheosis of that and he’s still feeling sort of empty and unfulfilled in a strange way.”

Murphy says Tommy’s battle with his inner demons will also take center stage this season. “They have very much come home to roost,” he says. “We’ve seen [his demons] through each season, but . . . he’s now very fragile, emotionally. It’s Tommy dealing with middle age and it’s also magnified a million times by the fact of what he’s been through as an individual in terms of the First World War . . . he’s sort of been medicating and ignoring this trauma he’s lived with for many years and, like time immemorial, these things can come back with a vengeance when men hit middle age.

“It’s not written in bold in the story,” he says, “but for me it’s an interesting thing to try and play given that I’m the same age as him.”

“Peaky Blinders” will return for a sixth season scheduled to begin shooting early next year (Murphy says he’s read the first four scripts). The Season 5 finale snared a series-record 3.8 million viewers when it aired on the BBC last month.

“I found the whole season as a combination of a psychological thriller meets a political thriller,” Murphy says. “I think the pressure put on Tommy by having children and having to reconcile the fact of who he is and what he does with trying to be a good and loving father . . . perhaps they’re ultimately unreconciliable.”