By Charles Scanlon
BBC correspondent in Seoul
Some of the cast thought Yoduk Story would never reach the stage
It is probably the least cheerful musical since Les Miserables -
a three-hour song and dance extravaganza set in one of North Korea's notorious labour camps.
Yoduk Story opens with goose-stepping communist soldiers and rousing revolutionary arias. Before long the action shifts to the hell of Yoduk - a North Korean prison camp that is believed to hold 20,000 political prisoners and their families.
It is the harrowing story of a celebrated state actress, who is sent to the camp with the rest of her family after her father is arrested as a spy - common practice in the North, where families down to the third generation are held accountable for the crimes of relatives.
Watching the play on opening night was a former camp inmate, Kim Yong-soon, who was imprisoned at Yoduk for eight years in the 1970s. Her crime was to gossip about the love life of Kim Jong-il, now the country's supreme ruler.
"Some-one had to tell the world about what's going on in the camps. As a former inmate it was an opportunity to remember the bitterness of the past and I couldn't help crying. I lost my parents and sons and my husband - and I had no way to vent my feelings," she said.
A former dancer in North Korea, Mrs Kim helped to choreograph some of the scenes for the production.
Some other refugees were concerned the musical would trivialise the sufferings of North Koreans, and said the storyline of love and forgiveness in the camp was unrealistic.
But the director, Jeong Song-san, says the production is an opportunity to dramatise the plight of North Korean prisoners and attract the attention of an apathetic public in South Korea.
He is a defector from the North himself, who was once briefly imprisoned for listening to South Korean radio.
"Even now unimaginably horrible things are happening in the camps," he says.
"But the South Korean government and the public are doing nothing about it. I hope this production will enlighten people and help stop the atrocities."
As they waited for curtain to go up on the first night, some cast members said they had doubted the production would ever get this far.
The original financial backers dropped out - the producers suspect they were scared off by pressure from the government, which is seeking to promote reconciliation with the North and is uneasy about such explicit criticism of the regime.
Mr Jeong says he received warnings himself from government officials and later received anonymous telephone threats.
The play is likely to stir a debate on North Korean human rights
"Discussion of the camps has become too politicised between those who sympathise with the North Korean regime and those that oppose it - that's why some people are opposed to what we're doing," said Kim Chung-kyung, who plays a concentration camp guard.
In the end, money was raised from individual backers and there was also support from groups that want to see more focus on human rights abuses in North Korea.
The government has abstained in recent years from UN votes condemning the North's record.
South Korean officials says privately that the North is holding some 200,000 political prisoners - but they argue that engagement rather than direct confrontation is the best way to bring about change.
Almost the entire musical is set at the Yoduk camp - it is portrayed as a nightmare world of public executions, rape and starvation.
The heroine is raped by the camp commander and bears him a child - but later survives to forgive him.
The theme may be too dark for some, especially younger South Koreans, many of whom find it hard to conceive of the horrors taking place just across the border.
"I'd heard of the camps but never took much interest. Seeing it has really shocked me - it's helped me to care more about what's happening," said Park Bang-hee, a student in her 20s, after the curtain went down.
The production can count on the enthusiasm of conservative and Christian groups - and is likely to spur debate on North Korean human rights, which have been overlooked in the rush to reconciliation.