My ears pricked up. It was the last day of school before the Easter holiday and our teacher was taking a break from the curriculum to tell us about a “legendary” sixth-century king who was reputedly buried just a couple of miles away.

King Fergus, he said, travelled from his native Scotland in 529 to seek a cure for his leprosy at a healing well in the northern part of Ireland. He never made it ashore. Hugging the coastline of the stretch of water now known as Belfast Lough, his vessel hit a rock and sank. Fergus was killed. When his body was recovered, it was taken by monks to a nearby abbey for burial.

As our teacher explained, the king's final resting place was situated at the intersection of two local roads on the lower slopes of a looming volcanic hill known as the Knockagh. Thrillingly, I had unknowingly cycled past the location on many occasions. This particular relic of the Dark Ages would be easy to explore. It was well within reach.

My nine-year-old’s imagination ran ahead of me. I lived in a neighbourhood characterised by post-war housing developments. It was a place where everything seemed new and a bit uninspiring. I had thoroughly explored a nearby Norman-era castle, loving its antiquity, but the tomb of a Scottish monarch was something else again. It would surely be something as large and imposing as it was dark and mysterious.

So a few days later I set off on my bike to find it. Jake, my best friend at school, was my partner in archaeology. Arriving at the spot where the roads met, we left our bikes propped up on a bush and hopped over a gate. I looked around expectantly for some sort of ancient monument or structure. There was nothing. “Come on,” I said. “It’s probably in the next field."

We walked around for perhaps an hour or so. Still nothing. Or so we thought. One of the fields was strewn with large stones. These, I learned later, were all that remained of the Abbey. The rest had been plundered for building materials. “Do you think it’s just a story?” Jake asked. “No,” I answered, trying to put a positive spin on the day. “I think he’s here somewhere. He's hidden, like King Arthur.”

As we got on our bikes, the sun was low in the sky. We had about half an hour to get home before dusk. I looked at the fields and tried to imagine the lost king. Maybe it was just a story. Fast forward three decades. I took my children to see the Disney movie, Brave. Guess what? It featured King Fergus. “I went looking for his grave once, I told them.”