It was always going to be a tough sell: "To make people believe that someone in a wheelchair who can barely move or talk could be as exciting as a guy in tights swinging down Madison Avenue in a superhero costume… it's a lot of money on the table."
Or so The Theory Of Everything's screenwriter Anthony McCarten puts it.
But find the money he did - all US$15 million (S$20 million) of it - if out of his own pocket initially.
"I felt compelled to get the rights and no one else was gonna help me do that, so I did it. It's like starting a benign religion and standing on a soapbox. Most people just walk past you and think you're a crazy guy," the screenwriter and novelist tells Life! at a press event in London recently.
Still, he had a secret weapon. Enter the unlikely rock star for a hero's life story: the world's most famous living scientist, Stephen Hawking.
Call it then, if you must, an investment in time - of McCarten's patience and the Cambridge don's physics.
"It's almost an antidote to the big Hollywood fairy tale," McCarten, 53, says.
"There's certainly a new audience for sophisticated adult movies… It's an older audience that is now going to the movies again - in big numbers."
In its finished version, the 123-minute feature film recounts the unusual life and loves of the severely disabled godfather of theoretical physics, based on a memoir by his ex-wife, Jane Wilde.
Opening in Singapore theatres tomorrow and directed by James Marsh, 51, the movie stars rising English actors Eddie Redmayne and Felicity Jones.
With emerging talk of potential Oscar nominations, cast, crew and producer are finally basking in their achievements.
Earlier last month, they received their laudations in London on Leicester Square's red carpet with the ultimate sanction: a rare co-appearance with the scientist in his trademark wheelchair.
"It was a moral duty to get his blessing, even if it was not a legal one," McCarten says.
He first spoke to Wilde in 2004 to ask for option rights to her book and she took seven years to say yes.
A second trip to meet Hawking was a nerveracking affair as the Cambridge don - severely stricken by his motor-neuron condition - could communicate his approval of the project only through his famous voice machine that produced one sentence every few minutes, via muscle twitches of his cheek.
McCarten points out: "Stephen is not interested in his disease - he is interested in his work and family and he keeps his sense of humour.
"The film honours that."
Of course, there is the physics too. This gets a whistle-stop tour that depicts Hawking's first major breakthrough on reverse-projecting black hole mechanics unto the proverbial moment of the big bang. It also segues into the denouncement of his earlier research in his later career with the publication of A Brief History Of Time in 1988.
While it would have been tempting to present the story as a Hollywoodesque triumph against all odds, McCarten and director Marsh (documentary Man On Wire, 2008) opted for a subtle love triangle.
"There were unusual obstacles, so there had to be unusual solutions," McCarten says, pointing out the arrival of an unlikely likeable third party in a love triangle in the film's second half.
"The decisions they made were so surprising, so unorthodox, that I didn't know what kind of love story the film would eventually be... that was a tricky thing to do because you run the risk of the audience losing sympathy for all the characters," he continues.
Jones, who plays Wilde, explains: "At the discovery of his illness, no one knew when Stephen was going to die. Time resonates differently and people make difficult choices."
The film opens in the 1960s with the commencement of Hawking's PhD in Cambridge and meeting Jane at a party. It tracks the couple, who have three children, through 25 years of life together up until their separation in 1995. After their divorce, he married Elaine Mason, one of his nurses, but this union also ended, in 2006, after more than 10 years.
Spoilers are easily at hand for any viewer with access to Wikipedia expositions of the demise of the Hawkings' marriage. However, the portrayal of this unravelling as a strange paean of hope against the backdrop of the physicist's degenerating illness is quietly sensitive and, on several occasions, magical.
Redmayne says: "There was a playful aspect to Stephen that I hoped to capture."
Jones adds: "We didn't want to do this as a stuffy period drama. I didn't want to impersonate Jane either, but try to get a sense of her essence. They were remarkably unsentimental, they just got on with things. They had no choice."
The two leads took four months to prepare for their career-changing roles - physically and emotionally.
Redmayne, 32, lost 8kg for the part and visited motor-neuron clinics, learning to embody the haunting debilitation of patients losing function of their muscles. Jones learnt to age 25 years in between toughening up and carrying the (albeit marginally reduced) weight of Redmayne for scenes of Wilde lifting Hawking out of wheelchairs.
It became a question of time - because of a restricted budget, filming was not undertaken chronologically. The cast jumped between several major periods of life frequently on the same day, not least on the first day of filming.
"I was a 40-year-old with three children in the morning and, in the afternoon, I'd be doing the scene of them meeting in their early courtship, outside the church," Jones, 31, recalls.
"You have to take off that entire baggage within minutes, it can be very wearying."
During location shoots at St John's College in Cambridge, both Wilde and Hawking, 72, turned up to observe proceedings on bicycle and wheelchair.
Wilde was not only a frequent visitor, but had also allowed Jones access to her family records, showing the actress old photographs in her Cambridge home - "sitting cross-legged on the floor, digging out these albums… she was very open".
While the 70-year-old former Mrs Hawking remained for the most part bemused and waiting by the sidelines as she watched the cast re-interpret her life, once in a while she would walk up to Redmayne and rearrange his crowning glory, laughing: "Stephen's hair wasn't like that."
Hawking, meanwhile, would be communicating through his trademark raised eyebrows - surreally and perfectly captured on film through Redmayne's careful facial impersonations.
Not wanting to be left out on the day of his location visit, the physicist - so the tabloids say - had cheekily asked Jones for a kiss, and she happily obliged.
The actress told newspaper reporters last month of the apocryphal episode: "I told him, you're amazing!"
Not bad at all for the diminutive guru of, literally, all time and universe.
But screenwriter McCarten reminds all with a smile: "If Stephen didn't actually exist and we created this character, who was in a wheelchair and speaks through this computer voice and is feted for his brilliant mind, it's gonna be science fiction... it would be Star Trek."
The Theory Of Everything opens in Singapore tomorrow.