When you’re interviewing someone for a story, preparation can be a double-edged sword. Last month, I travelled to South Korea to visit a bevy of friends and taste as much kimchi and spicy pork wraps as I could. I brought my audio recorder just in case I found time to work on a story for Terra Informa, and in my last few days I found a place that seemed to ripe for narrative.

North of the Han River, I read, downtown Seoul was thinly sliced in two by an ancient stream: Cheonggyecheon. There’s a pretty well-established history that’s told of Cheonggyecheon’s life over the past hundred years: slums grew up around its banks, it became increasingly polluted as a home for laundry and sewage, and eventually the municipal government decided it was easier to cover the whole area over with a freeway than to clean it up. Then around 2000, Seoul’s mayor decided to lead the charge on rehabilitating the stream, and the city transformed it at great expense into a fashionable, healthier tourist attraction. The project bolstered mayor Lee Myung-Bak’s reputation, and helped catapult him into the presidency.

Like any good reporter, I wanted to be more than just a stenographer for this official narrative. I landed on two approaches for getting a fresh angle. First, I’d interview a local historian and ask some hard questions about what happened to the people who lived in those slums. It seemed like an obvious injustice that while they were told to move, billions of dollars were later poured into cleaning up the stream for tourists and nearby financial analysts on their lunch break. Second, I’d ask a scientist who studied water quality in Korea to give me context on how polluted other bodies of water are around Seoul.

I was able to arrange for Seoul’s city government to assign a storyteller/tour guide named Ho Park to walk me down the stream and answer some questions about its history over the past 600 years. I had my questions ready, and as we strolled past symbolic pieces of stone and renovated ancient bridges, I tried to press him on why the poorer residents were moved, rather than being able to benefit from a cleaner waterway themselves. While he gamely told me the name of a neighbourhood they’d been relocated to and tried to answer my questions, I could tell he was getting tired of them.

Finally Park said, “Have you ever been hungry?” I admitted that I hadn’t.

Then he told me a different story about Cheonggyecheon. Look at it from the perspective of the country after the Korean War, he said. Millions of casualties, both countries in ruins, and many of those left were desperately poor. South Korea didn’t have the kind of money to think about environmental health, he said. The whole country, and certainly its iron-fisted dictatorship, were focused on economic growth.

Today, Seoul is a mostly-affluent, sometimes futuristic city. You can swipe your RFID-enabled transit card to get on about a dozen subway lines that snake through the city, have your butt heated the whole way, and be right at home watching soap operas on your smartphone along with all the other passengers enjoying seamless 4G connections through the tunnels. When I first visited Cheonggyecheon, I wandered past a crowd of photographers gathered around a fake backdrop for a North Face photo shoot.

Now, said Park, was the time to think seriously about cleaning up air quality downtown and get carp and marsh snails back in the streams. Ecological health is a luxury for the rich, essentially.

It wasn’t the story I came for, and it wasn’t one I was comfortable with. But it was the honest perspective I found from both Park and the scientist, so it’s going to be the thread of my story. Sometimes, you have to be willing to toss out your well-prepared notes and follow your nose.