“It’s the kind of film that’s very funny until it’s not funny,” says Bennett Miller of his US competition entry Foxcatcher, backed by Megan Ellison’s Annapurna Pictures and Columbia Pictures.

“The absurdity of the characters is funny.”

Foxcatcher has been a nine-year labour of love for Miller, ever since he read a newspaper article about the bizarre true-life episode and tried to make the film the follow-up to his 2005 narrative directorial debut Capote.

“It’s the story of John du Pont, who was the heir to the du Pont fortune, and how he came to murder a wrestler,” he says. “It’s set in the mid-to-late ’80s in Pennsylvania. Du Pont is in his 50s, living on a 500-acre estate in the house where he grew up, with his 90-year-old mother living downstairs.

“He decides he wants to get America’s best wrestlers to move into the estate and build them a training facility so he can be their coach and lead them to victory over the Soviets in the [1988] Olympics in Seoul.”

After his early efforts to find backers for Foxcatcher floundered, Miller went off and made Moneyball. Afterwards, on the advice of agents, he approached Megan Ellison, the Hollywood financier who is not afraid of backing challenging fare. The young producer-financer committed quickly. Eventually Columbia Pictures would co-finance with Ellison, but it was she who dived in first and she who made Miller feel comfortable about pulling out of the initial world premiere gala slot at AFI FEST 2013.

Feeling rushed, Miller heeded his producer’s advice and withdrew from the November festival, some 10 months after production had wrapped in Pennsylvania. The timeline offers a hint about the intensity of the post-production cycle.

“It’s been a huge editing process,” says Miller, who earned an Oscar nomination in 2006 for directing Capote. “These films are not made in the normal way. I don’t work from a screenplay.

“They’re organised in an outline and the scenes we decide to shoot we explore in rehearsal and again on the day with the actors. It makes for a much more complicated editing process.”

Miller will remain eternally grateful to Ellison for her support. “I don’t think there’s anybody like her working out there.”

He owes a debt of gratitude to his cast, too. Steve Carell nails it as du Pont, Miller says, because we don’t expect him to inhabit this kind of character. “Steve has complexity to him and a strain of darkness and awkwardness and intelligence and it worked.

“I cannot imagine anybody in any of these roles other than the actors in there. Channing Tatum and Mark Ruffalo play the brothers [wrestler Mark Schultz and Dave Schultz] and all three of them are extraordinary.”

The film has its world premiere on Monday [19] in Competition. SPC will release Foxcatcher on November 14 and Annapurna International handles sales outside the US.