He pulled up and waited. A boy approached his car. The boy could not have been more than 10 years old. The boy produced a gun and told Clarke to "give me everything, quick, or I will kill you."

Clarke, a priest, didn't have much money on him. He fished in his pocket and pulled out what he had and handed it over to the gunboy. Then the lights changed, and he drove off before any further discussion could be engaged on his prospects of staying alive.

"It was a funny experience to hear a child of 10 tell you he'd blow your brains out, " Clarke remembers. "And he probably would."

The incident stayed with Clarke and was one link in a chain of long experience that prompted him to do his damnedest to keep 10-yearolds away from guns. In the city of Sao Paulo, that is no small task.

Brazil's largest metropolis is home to 18 million people, the majority of whom live in abject poverty. The gap between rich and poor in the city is among the largest in the world. One per cent of residents earn more than the poorest 50%.

Two thirds of the population are under 20, and six in every 10 people live in the favellas, or shanty towns.

In such a cauldron, drugs gangs rule and police corruption is as likely to involve gratuitous killing as skimming drug profits. Crime is seen in the most immediate instance as a way to put food in your mouth. And every day, more and more children pour into the city from the rural north east of Brazil, fleeing hunger, chasing dreams. Most are sucked into the vortex of crime and drugs, often ending their short lives at the sharp end of a needle or bullet.

Carlow-born Fr Pat Clarke wanted to make whatever small difference he could. His experience in the city had shown him that food alone will not divert children from a culture of drugs and violence. They also needed to nurture their creativity.

"Who says that art isn't food?"

he asks. "Who says that music isn't food? Who says that spiritual life isn't food?"

He set up an arts and culture centre in the sprawling shanty town of Villa Prudente 20 years ago. Against impossible odds it is still going strong, providing an oasis, establishing links with Dublin's National College of Art and Design (NCAD), and, above all, ensuring that the favella has given up a few less wasted lives.

Esperanza Productions' documentary on Fr Pat Clarke invites the viewer into a world that might appear to be plucked from another time and planet. The company's principals, Anne Daly and Ronan Tynan, have a record of exposing the harsh realities of the developing world.

Entitled Where 2+2=5, the theme running through the film is how the impossible can be achieved. In common with Esperanza's other productions, Where 2+2=5 is writ across a bleak canvas, saved from total despair only by the power of the human spirit. The battle against the impossible began when Clarke set up the project.

"We set up in a shed that was used to wake the dead, " he says.

"Then a family with nine children invaded and we were out on the street until they left."

Even now though, while the project offers an oasis, it is not removed from the world outside.

Esperanza was only allowed to film after negotiations with the local drugs gang. Two years ago, there was a shoot-out in the environs of the project in which 18 people were killed, including one who was attending the centre.

The local drug boss kept Fr Clarke and his people under protection, but he was shot dead a few months ago in a dispute. Now the priest must cautiously build up a rapport with the dead leader's successor, but on the whole, the criminals support what is being done.

"These bandits, they respect the project. They know me and they look after me, " Clarke says.

Now, in the shed where they used to mourn another lost life, the children are engaged in music, dance, painting and drawing.

Some talk of the different path their friends have taken. One child remembers where he was at a few years earlier when he came in contact with Clarke's project.

"When I was seven I was going into bars and on the street, " he says. "Now I see my friends still doing it. Some of them are using drugs." Another child, recently arrived at the project, tells how his mother was shot dead.

Exploring creativity allows the youths to express their worldview.

One teenager has created a mosaic, representative of the people being suppressed under the boot of a politician. The work is a practical example of the different route the project provides. Frustration and despair can be expressed in art rather than in violence.

"The waste of human life is shocking, " Clarke says. "Despair would be to look at the statistics.

Hope is to look at the mosaic."

Seven years ago, Brian Maguire, professor of fine art at the NCAD, was visiting Sao Paulo when he happened across the project. He got involved and ensured that some of the work undertaken went on display at the Sao Paulo Biennale, the prestigious modern art museum in the city.

For Clarke, the major success has been to harness the will among elements in the community to work together to provide an alternative for the children. He has, he says, been guided in his approach by the work of Paulo Freire, a Brazilian educationalist.

"He said, 'Walk with the people, not behind them and not in front'."

Clarke remembers. The evidence as produced by 2+2=5 suggests that Clarke has kept to the letter of that nugget of advice.

'Where 2+2=5' broadcasts on RTE One tomorrow night at 11pm