I was at pains to try and make this not feel like a playwright's movie," says David Auburn, the award-winning playwright of Proof, whose directorial film debut The Girl In The Park has its world premiere at the Toronto International Film Festival this week. "I wrote it for the screen. I wanted to explore the aftermath of a tragedy, but not the immediate aftermath. I wanted to jump 16 years ahead. That struck me as something cinematic to start with."

The tragedy in question is the disappearance of a six year-old girl from a New York City park. Her mother Julia (Sigourney Weaver) is devastated and leaves her husband and son, only to return 16 years later. Once back in the city, she is haunted by the loss of her daughter but finds new life in her friendship with a troubled young woman (Kate Bosworth) who she believes could be her daughter. Alessandro Nivola co-stars as her neglected son, with Keri Russell as his fiancee.

"I had always wanted to make a movie. I have been obsessed by movies and the theatre since I was a kid." Auburn had two previous experiences of working on films - one an adaptation of his play Proof directed by John Madden, which he says was "difficult", the other big-budget romance The Lake House, for which he wrote the screenplay for Warner Bros but never met director Alejandro Agresti. "I realised fairly quickly you have to direct if you want control of your own material."

The Girl In The Park shot for 25 days on, says Auburn, an unusually large number of locations in the city. "The biggest challenge was the stamina that directing requires," he says. "Writers have it pretty easy, they can take a midday nap. Directors have to be on the game for 14 or 15 hours a day, every day."

He says he relied on his director of photography Stuart Dryburgh (The Piano, The Painted Veil) to help him lift the film visually from the realms of a TV drama. "We used wide lenses and the widest-aspect ratio. And we tried not to use too many close-ups as the material was so close to melodrama already."

"Having so little time forced me to think about what the scene was about and communicate it in two or three set-ups. Stuart brought endless visual ideas to it. I felt safe hiring him as he wasn't just used to lighting huge movies. He was very generous in giving me menus of options."

Auburn says the film was the most challenging thing he's done. "It's been so all-consuming for two years that I suppose I better start thinking about getting a job. I've no idea what the prospects are for the movie. But I would like to do it again - maybe with a little more time for the next, say 30 or 40 days."

The film was produced by Sean and Bryan Furst with backing from Australian talent agency RGM Entertainment via a loan-guarantee programme from Singapore as well as Singapore production company Oak3 Films, Germany's Witox Filmproduktions and QED International, which is handling sales. Cinetic Media is representing domestic distribution at Toronto.