The early 1980s were dire, filled with predictions of nuclear war and annihilation. The future filled him with dread; he felt that any hope of getting past his 20s was foolhardy.

But then, one January evening in 1990, he found himself on the streets of Prague, caught up in Europe's "season of miracles".

Sitting in the restaurant of an old art nouveau hotel in Wenceslas Square, he heard the beating of drums, and ran outside to find people protesting.

The Cold War was over - the Velvet Revolution had seen a peaceful transition of power. The protest was against the StB, the secret police. It too ended peacefully.

But for 25-year-old Fidler it was exhilarating.

"Suddenly the future was back - you could have a future again," he says.

"I think my first visit there was at a point in my life where I shifted my temperament from pessimism to optimism about the nature of the world, because things like that aren't supposed to happen in the world.

"But sometimes they do, and I was there and I saw it."

His sense of wonder at the strange and beautiful city - at its through-the-looking-glass skew, the uneasy liminal qualities of the cobbled streets and layers of history - has never left him, even after an absence of almost 30 years.

The writer and broadcaster has, in the intervening years, been part of the iconic comedy trio the Doug Anthony Allstars, married, had children, built up a reputation as a much-admired radio host, and written two books.

And now, a third - The Golden Maze - an ambitious history of Prague, one that begins with his own, personal starting point for a love affair that has never waned.

He says it has taken nearly three decades to get around to writing it, mainly because he needed the distance of time to forgive his own callow youth.

"I had to be a bit grown up, I think, in order to write such a book, and also to stand outside my youthful self and have the perspective of 30 years," he says.

"And of course, so much as changed. Not only have I got somewhat older - I'm in middle age - but also the city has changed so utterly, and yet stayed the same."

Returning to Prague in 2018 was bittersweet. The city had been transformed into a glittery tourist mecca. Crooked roofs were repaired, buildings repainted and restored.

It wasn't quite the odd, otherworldly place of his youth.

"It's the dilemma of the traveller, isn't it?" he says of the now-constant stream of tourists flooding into squares and down laneways, peering into shops that were once filled with oddities and notions, and now sell commercial tat.

"It had lost something of its mystery as a result, and its strange uncanny quality ... But you can still get it if you get up very early in the morning or if you walk through the place past midnight.

"There it is again, that weird, odd feeling that you get, nowhere else in any city I've ever been. It's one of those liminal places where its name as a city is so perfect - Prague means 'threshold'. And it has always felt like a threshold to something that feels otherworldly to us."

Otherworldly or not, his fascination with the city has rattled around his consciousness since that first visit and by 2018, it was time to pay attention.

Regular ABC radio listeners might have noticed Fidler's extended absence in early 2019; he had accepted a Prague City of Literature writers residency and spent several months living in an apartment there, wandering the city and peering into its nooks and crannies.

He says it made all the difference when it came to telling the city's story - approaching casually, curiously, an outsider looking in.

He had always been a keen reader of history - he studied at the Australian National University in Canberra in the 1980s but gave himself something of a second education during his years travelling and performing with the Allstars.

There was plenty of sitting around while on the road, and he was, he says, constantly reading, almost always history.

His knowledge of 20th century history, told from a western perspective, was solid. But when it came to Prague, he found he knew very little.

"When I arrived in the Velvet Revolution period, the place was just like a great big enigma to me," he says.

"It's so beautiful and elaborate and covered with words I couldn't understand. Like the Jan Huss memorial, which is this giant wedding cake of a commemorative statue in the middle of the Old Town square - I had no idea who he was, and the language on the base of it was completely unreadable to me.

"I didn't know about the Astronomical Clock in the Old Town square, one of the most stunning things that was ever created in all of the Middle Ages. What is this doing here, how did this come about, how did it get to be so beautiful? When was it made? I was filled with questions about the place."

He understood that he could creep up to the history of the place, and take it by surprise, telling it through the eyes of an outsider, with nothing at stake but curiosity and love.

He also discovered that his view of history - the long view, the legacy - is quite different from how we see it.

For western democracies, the Second World War - the one that saw the British and the French conniving to offer Czechoslovakia as a bone to keep Hitler happy - can be seen, in hindsight, as a morality tale.

There's a narrative that once these democracies were roused to action, wrongs were righted, Hitler was defeated, and order was restored.

"That proved that good had triumphed over evil. But in Prague, they had to draw very different conclusions," Fidler says.

"They had a really good, strong, decent democracy, and a prosperous economy and an independent country that had a great degree of freedom for a good 30 years, and that meant nothing in the end.

"It was smashed by Hitler and the lesson they learnt was like the lesson of the thug who puts his fist in your face, and says all your talk about human rights and democracy is lovely but I'm just going to punch you in the head and take everything you have, and maybe kill half your family.

"So the lesson they learnt from that was that might makes right, and then a great many of them signed up for communism because it seemed like the most pressing and the most powerful moral rebuttal at the time to Nazism, and the failure of the western democracies to come to their defence."

Stalin's communism led to a further, more drawn-out agony - a further lesson in the mighty overcoming the vulnerable.

"They've seen their best instincts and their humanist values be utterly destroyed by ruthless dictators. And that's why when the Velvet Revolution came around, and you have a leader like Vaclav Havel, the playwright and dissident who leads the revolution with very moral language, and talks about dignity and really means it - that's why it's so powerful, this language, this kind of moral recovery."

Alongside the city's historical travails, though, is a rich tapestry of myths, legend and folklore that's woven into the fabric of daily life.

The book opens with Libussa, the fabled witch-queen, standing on the edge of a cliff and seeing a vision laid out before her.

"I see a great city," she says. "Its glory will touch the stars."

She then instructs her attendants to go into the forest where they will find "a man making the best use of his teeth at midday".

The courtiers obey and soon find a man sawing a block of wood. He tells them he is making a threshold for a house - a prah in Czech, this giving the city its name.

Streams of modern-day tourists notwithstanding, these are stories that, if you stand in Wenceslas Square at midnight, or find yourself wandering an unfamiliar cobbled street, seem just as real as the crusades, wars and revolutions it has weathered over centuries.

And there's something else there, something Fidler noticed straight away, and that many others have also seen and felt.

"It takes you a long while to put your finger on it. You have this eerie sense of almost deja vu while you're there," he says.

"After a while you realise, of course, this is the imaginative landscape I lived in when I was little.

"And you realise all of us have this in our minds, we have these landscapes we used to live in when we were little that we've just not really bothered to revisit.

"They're still there, and they still exist in some strange backwater of the synapses and neurological connections in our mind, but you can revisit them, and when you go back to Prague, suddenly you're there again, and it's so real all of a sudden, it's quite disconcerting."

The fairy tales, though, are the dark ones, Brothers Grimm rather than Disney, the ones meant to scare children into obeying their parents. The ones that don't have happy endings.

The boy who cried wolf gets eaten, Hansel and Gretel have no home to go to, and the wicked stepsisters lop off parts of their feet to fit into the glass slipper.

"That's what Prague is for me ... it's not a mirror of heaven. It's otherworldly, but whatever that other world is, it's not heaven," he says.

"It's not hell either, I don't know what it is. It's something you can't quite touch, it's so tantalising and I think that creates, in my mind anyway, that sense of tension and expectation that is always there with me in the city."