“Oh! Wow! A secret tunnel. Here in Seoul?” mutters Ji-Min, rubbing his hands together. “Ending at the Han River?”

“That’s got smugglers and criminals written all over it!” says Steve.

“Possibly?” mutters Albertina.

“But for now! We need to continue researching the possibility and whereabouts of where this tunnel starts and finishes!” adds Nazz bluntly.

“Yeah! Good idea, Nazz,” says Ji-Min excitedly.

“I think we have two main areas to look at closely when we hit the streets,” says Steve. “Namsan Park and the Han River banks by the Gangnam Bridge!”

“Agreed!” say Zig and Albertina simultaneously.

Days later, Ji-Min, his team, and the ZandaBots, wearing hair wigs and human clothes, set off for Namsan Park.

When they reach the park, Ji-Min and his team meet the park’s Senior Ranger, Mr Eun, as pre-arranged by Ji-Min two days earlier.

After all the introductions and greetings, Mr Eun leads Ji-Min and his team to an area known for its small caves, crevices, and holes in the rocky ground.

Ji-Min, the ZandaBots, and the guys use Steve’s grid method to search all day, stopping at lunchtime for rest, food, and water. After continuing to search all afternoon, they still don’t find any trace of a tunnel or anything that resembles one.

As early evening approaches, Steve and Ji-Min decide to stop searching for the day, much to the delight of Zig, Max and their friends.

“Steve, it will take a month to search this park from one end to the other,” says Ji-Min as all the guys pack their maps, compasses and gear into their rucksacks.

“Yeah! You’re right. We need some help!” he adds.

“Sir!” says Mr Eun, looking at Ji-Min.

“I’ve been thinking? The only area I can think of that might meet your criteria is a high, narrow passage on the farthest southern edge of the park. It’s not a tunnel, but this slim passage leads under the Sowol Road outside the park and continues a short distance, running adjacent to the Grand Crane Hotel. Then it comes to a dead end!” explains Mr Eun.

“Fascinating!” replies Ji-Min. “Is it possible for the two of us to meet you here tomorrow to check out that passage?” he adds, gesturing towards Steve.

“Sure!” replies Eun. “I’ll meet you here at nine o’clock tomorrow morning!”

“Great! Thank you, Mr Eun,” says Ji-Min before shaking hands with the ranger.

Everyone thanks Mr Eun before climbing into their minibus and returning to Ji-Min’s office building.

“This way, please!” says Mr Eun the following morning, as Steve and Ji-Min walk toward him, standing just off the car park in a group of trees.

“Here we are?” says Eun, after walking for 20 minutes or so and stopping in front of a short row of trees, several meters in front of a rugged rock face about five meters high.

“What! Here?” asks Steve, looking around.

Mr Eun removes his rucksack and walks behind the group of tall trees, which are spaced closely together.

Ji-Min and Steve follow the ranger.

“Oh! Wow!” says Ji-Min, looking at a slim gap in the rugged rock face, which slopes upward at an angle.

“Follow me!” says Eun, with a touch in one hand as he squeezes into the gap before disappearing inside.

Steve and Ji-Min follow closely, also equipped with touches.

All three men use their touches to illuminate different areas of the walls, floor and ceiling as they continue to follow the dark, damp, narrow passage, which varies in width and height until it ends where a three or four-meter stretch of black, cold-looking water, which runs down the walls of both sides of the passageway, before disappears into the ground in front of a solid rock face.

The three men shine their torches on the rock face, which marks the end of the narrow passage, as water constantly drips from the ceiling into the pool of water. Then, the men turn to retrace their tracks and emerge into the park’s sunlight a while later.

The following day, Ji-Min’s team gathers in his office, where the two CEOs explain their journey into the slim passage in Namsan Park.

“Anything to add, Steve?” asks Ji-Min after his explanation.

“No! Let’s move on to the Han River,” replies Steve, looking around the group as they concentrate on Ji-Min. “Yeah! Okay!” mutters his friend.

“Right, guys, ZandaBots! This afternoon, we’re going for a boat ride along the Han River, courtesy of my friend’s boat!” continues Ji-Min, looking at Zig and the team.

“Nice!” says Dal as everyone expresses their delight.

“Interesting!” mutters Nero. “Do you want to check out the banks of the Han River from the waterline?” asks Nuno.

“Exactly!” replies Steve, putting a thumb up toward Nuno. “Plus, we want to go under the Gangnam Bridge,” he adds.

“We don’t know what we’re looking for or what we might find. But we’re eager to explore that area!” says Ji-Min.

“Exciting!” mutters Albertina, looking at Zig.

Mid-afternoon, Ji-Min, Steve, and their team, including the ZandaBots, are on an average-sized boat on the Han River, nearing the Gangnam Bridge.

Ji-Min captains the boat and slowly guides it under the river’s large bridge, along the bank.