THOUGH awards acceptance speeches can be rambling affairs, no one has yet cited their son smacking them in the face with a baseball as an inspiration.

Stacie Passon, director of a new drama, Concussion, might just do that one day.

"My son has a fantastic pitching arm," says Passon. "We were playing a game of catch and my daughter was screaming in the background. I missed the ball and it hit me on the head. I had a concussion, it was very bloody as well. Poor thing, he felt so very sorry. We got into the car and I just began to cry. My wife decided at that point I needed to do something else besides mother."

After the headache abated, Passon wrote Concussion, the story of a suburban mother in a sexless but otherwise happy gay marriage who decides to start a secret life as a hooker. A hit at Sundance and picked up by The Weinstein Company, the film opens in Scotland this week.

The lead is played by Robin Weigert in what is a breakthrough part for the actor best known as Calamity Jane in Deadwood. Working with a micro budget, and thinking the film would play at only a few venues, Passon also cast her own children. "I asked my wife and my mother and a bunch of other people and they felt that somehow it would be some sort of time capsule." She is not afraid it will turn them on to acting? "Oh God, I hope not," she says, laughing.

While Concussion is Passon's debut feature, she has had a long career directing and producing ads. That meant she could skip the traditional stage for novice directors of making short films.

"Directors really only shoot 30 days every couple of years. I was always shooting. It's something that comes quite naturally and quite fast to me."

Concussion is produced by Rose Troche, the pioneering director of 1994's Go Fish. Lesbian drama in the movies has come a long way since then, to the extent that Concussion is being seen not as a niche movie but a film with crossover appeal. "It's a film for everyone, for all marrieds," says Passon.

Being about gay marriage, it has also caught the mood of the changing times in America and the UK. Ultimately, Passon believes, Concussion defies sexual categorisation. "It does not seem like a straight movie or a gay movie. At the end of it I looked at it and didn't really understand what I had made."

What is noticeable is that the couple's sexuality is simply taken as read. There is no big coming-out scene, no heavyweight discussions about gay marriage. What the characters experience, Passon reckons, is the same as anyone in a long relationship. "The film makes the case for everybody to be a little bit more queer."

Meaning?

"Put sex squarely down the middle of your life and think about what it means it you. Don't cut yourself off simply because you are in a 20-year marriage. Understand your partner, understand his or her needs, and if you find you are at a point where there is a fork in the road, because your partner can't give you what you want, or your needs aren't matched, then what do you do? (The film) asks the question."

It's a pretty radical question, I suggest.

"But that's what movies are for, right?"

She is looking forward to the day when there is no Berlin Wall between gay and other cinema.

"To the extent we feel we are a unique and creative audience there will always be gay and lesbian cinema. Our stories will become more mainstream as people understand, less of a curiosity. We will begin to mesh within the heterosexual framework, so there will be blockbuster movies with gay characters in them, that kind of thing. It would definitely be good for my kids to be able to see that."

Being picked up by The Weinstein Company is the stuff of which debut filmmakers' dreams are made.

"That helped the film get sold in so many other countries, people took notice of it and felt there was something there because they are amazing curators and arbiters of taste in worldwide cinema.

"To the extent it is going to mean something for my career I am not really sure. I am gearing up to shoot something but it will be something very small, I don't know if it will be successful, I don't know if it will be with main actors, but I just want to continue to do work."

Keeping it small, says the New Jersey resident, is what women filmmakers have to do in America at the moment.

"In Hollywood it is very hard to monetise a woman's story. It is very hard to say, 'This will work'. To the extent it works for a distributor is not really my concern right now so I want to keep it as small as possible to make the film I want to make. My career is not my primary focus."

All things considered, then, she has reason to be grateful to her son, now 11, for that sore head day.

"He felt bad about it for a moment, now he realises he was a hero for doing it. He is never seen the film of course, but he loves the fact his mum has found a purpose. That is good for him too."

Cineworld, Renfrew Street, Glasgow, and Cameo, Edinburgh, from tomorrow