It’s hard to imagine the courage it took to flea East Germany – a brutal dictatorship that divided Berlin by bricks and barbed wire for decades.
It’s even harder to imagine why anyone who escaped would risk their life by going back in again.
But that’s exactly the choice Joachim Rudolph made after arriving in West Berlin in 1961.
Tunnel 29 is the extraordinary true story of a group of students and refugees who dug a tunnel right under the feet of Berlin Wall border guards to help friends, family and even strangers escape.
It’s also the story of how American TV channel NBC funded it in return for exclusive filming rights.
The forgotten tale has been brought to life on a BBC Radio 4 Podcast to mark the 30th anniversary of the fall of the Berlin Wall today.
But producer Helen Merriman didn’t set out to make a history podcast.
‘The idea came to me about a year ago’ she told Metro.co.uk
‘I didn’t set out to make a history podcast. It was the context of doing research about Donald Trump and the wall he has proposed, and in the context of that I discovered that there are all these other walls being built right now. One third of countries actually have some kind of wall or barrier.
‘I was interested in looking not so much at the politics,but also just the practical side of things. What happens to a city when you build a wall overnight?
‘The other thing I discovered quite soon, wherever you build a wall, you will have people who will try to escape and find ways round them.
‘I thought this was quite a clever way of looking at the contemporary theme of walls and barriers, but through the lens of an escape story.
‘That’s how I came across Joachim’s story.’
Tunnel29 is told through the eyes of Joachim Rudolph, an engineer student who crawled through a field in the middle of the night to make it into the West aged 22.
His success story was a rare one. People jumped over barbed wire, swam across the River Spree in bathtubs with their babies and threw themselves out of houses at the border in the hope someone would catch them on the other side.
The risks of escaping were huge – yet just months into his new life of freedom, Joachim, now approaching 80, agreed to help two students who came knocking on his door asking for help in building a tunnel back in.
Merriman, who spent over a week interviewing Joachim for the podcast, said: ‘There are so many times when I said to him, this is just extraordinary what you did. There were so many moments when he could have just said no.
‘Why would someone risk everything to dig back into a dictatorship they have just escaped from?
‘I would say to him, why did you keep on going? And he would say, ‘well, why would I stop?’ He was extremely humble. I don’t get the impression he thinks he did anything significant. ‘
It’s hard to imagine how anyone could listen to Tunnel 29 without realising the significance of Joachim’s bravery.
He and his friends spent eight hours a day building a tunnel under the so-called ‘death-strip’, where they were so close to East German border guards they could hear them talking.
Their first tunnel flooded, their second one was betrayed by a Stasi (secret police) informant – and yet they still managed to save 29 people from a brutal regime.
‘I think the thing that I took away from it most is just the extraordinary heroism you get from ordinary people who find themselves in extraordinary situations’ Merriman said.
‘There were stories of other tunnelers who did not make it, who were buried by earth, who were discovered by the Stasi (secret police) and shot.
‘The tunnelers knew about these stories – they knew that at any moment it could go wrong and yet they carried on, the bravery of these people was just extraordinary.’
‘This was their lives, they lived through this. All I wanted was that people would understand what it was like for those people, and their heroism, even if they don’t see it that way.’
About 40 people were involved in building the tunnel under the Berlin Wall.
But unlike the other plotters, Joachim had no connection to the East Germans they saved (although he later married one).
Having spent most of his life where everything down to his toilet breaks were controlled, he struggled to adapt to the freedom in the West.
Tunnel 29 is based on 2,400 Stasi documents and interviews with survivors – but it feels more like a pyscological thriller than a history podcast – which is exactly what Merriman was going for.
She said: ‘Even when I made it, it didn’t feel like a history story. It feels like it could be an escape story of any wall that’s up today.
It’s a refugee story, so there’s a contemporary resonance of someone living in a country that makes life difficult and finding it hard to make sense of the new place you arrive in.
‘Anyone could be born in a county or city where a wall is suddenly built in front of you. For me that’s a real question, what would you do?’.
All ten episodes of Tunnel 29 are available now on BBC Sounds.