By Steve Condie
Producer, One Night in Bhopal
In the early hours of 3 December 1984, in the Indian city of Bhopal, a toxic chemical leaked from a factory in northern India leading to the world's worst industrial accident. BBC 1's One Night in Bhopal tells the story of the tragedy through the eyes of those who were there.
In late July of this year our BBC team drove through the gates of the Union Carbide factory in Bhopal.
We were met by a mean looking squad of iron bar wielding guards.
They instantly and emphatically demanded our "permissions", the magic slips of paper that ease you through the bureaucratic jungle of Indian life.
ONE NIGHT IN BHOPAL
Wednesday, 1 December, 2004
2100 GMT, BBC One
Hindi language version available on interactive TV
Thankfully, Sarah Waldron, the Assistant Producer on the team had already visited "The Collector of Bhopal" in his Kafkaesque office and secured our "permissions".
The iron bars were lowered and we were guided into the grim remains of Union Carbide, Bhopal.
As we drove through the factory grounds I tried to pull into focus the photographs of a bright, shiny factory I had studied in the office in London.
The ruins are a powerful symbol of an American dream that turned into an Indian nightmare
But the gleaming pipes and whitewashed modernist 70's buildings were nowhere to be seen.
Instead we were confronted with a mangled, looted, fetid wreck.
Rust devours the pipes and dust lies in 20 year thick piles.
The ruins are a powerful symbol of an American dream that turned into an Indian nightmare.
The story of five extraordinary people in One Night in Bhopal
We were accompanied on our tour of the plant by Dr Kumkum Saxena.
She had been Union Carbide's medical officer in happier times, when the factory felt like the future.
She showed us the control room of the unit that made Methyl Isocyanate (MIC) the chemical that killed thousands when it was spewed into the Bhopal night.
She guided us through her old medical centre and she frequently coughed and covered her mouth as she caught whiffs of the chemicals that still circulate in the shattered surroundings.
Kumkum had travelled from her home in the US to revisit the city and the factory for our film.
She had never spoken publicly about her time at Union Carbide.
As we traipsed through the factory, dodging the monsoon puddles and stray cobras. She told us how she had joined Union Carbide full of hope but became disillusioned as the plant's management ignored her pleas for a more rigorous safety regime.
Kumkum was one of five extraordinary people we met in Bhopal.
They came from all levels of life in the city but in 1984 they had two things in common.
Firstly, they had lives that were full of hope with young families, good jobs and real prospects.
Secondly, they believed in Union Carbide. "One Night In Bhopal" is their story.
The film combines dramatisation and documentary to chronicle Union Carbide's vision of making a miracle pesticide in Bhopal and how that dream was betrayed.
We reveal the sequence of events that led to the disaster and horror and terror in the early hours of 3 December, 1984. And we examine the appalling long term legacy.
Today, like many thousands of others in the city the characters in our film struggle with illness and injury, financial insecurity and deep, profound grief.
For them and many, many more the Bhopal gas disaster is not an event that occurred 20 years ago, it is a daily reality that will burden generations to come.
One Night in Bhopal was broadcast in the UK on Wednesday, 1 December 2004 at 2100 BST on BBC One. A Hindi language version was available on interactive television.
It was also broadcast on Saturday, 4 December 2004, on BBC World. Please check the BBC World TV listings for details of transmission times.