An Uncooperative Tunnel

The cutting became steadily more narrow after the little station, changing from a flattened path on the side of a hill to a narrow track obviously carved right out of the rock of the valley wall, looking barely wide enough for a train carriage.
“The views are spectacular, at least?” Bug suggested as they walked along.
Cy took a short break from walking ahead to peer over the edge.
“I’ve never looked down on the top of a tree before.” He commented, then carefully stepped back to the middle of the tracks. “It’s … Kind of creepy.”
He looked the other way, at the rough stone wall beside them, and sighed, giving it an accusing look.
“I can’t tell whether anyone else came this way. Sorry.” He apologised. “Lumpy probably could, but there aren’t enough plants or twigs or anything to get broken or squished.”
Luce shrugged.
“Mister Station and Lumpy both thought that this was the most likely option, even if they couldn’t see how it had been done.” She said. “So we’d have had to check it anyway, I guess?”
They trudged on for a bit.
“I’ve been wondering about the river.” Bug said, to nobody in particular.
Cy said something indistinct from up front, then called out ‘Hang On’ and stood perilously close to the edge, waiting as Bug and Luce pushed the railcart by.
“Sorry, what about the river?” He repeated, falling into place walking behind them. “We haven’t crossed it yet, have we?”
Bug shook her head and gestured to the rock wall beside her.
“No, we haven’t, and I don’t think we’re going to. Not this close to the valley wall; I don’t think that’s how rivers or valleys work.”
Luce nodded out towards the open side of the tracks. They were high enough now that many of the trees on the slop below were too short to block the view, so they could see out over the whole valley, with the river glinting occasionally through the sea of trees, and a faint wisp of smoke or steam just visible from Mister Station’s place.
“Pretty sure the river is down there, so unless it does some weird waterfall thing, I don’t think we cross it anywhere forward of here either.” Luce agreed. “That other line out to the mine probably does though, if it goes to the other side of the valley.”
She paused then, running back what she’d just said and wondering why Bug had been thinking about it.
“But if this line doesn’t cross the river … “ Luce continued slowly.
“Or even cross any big streams?” Cy added, not entirely sure where this line of thought was going, but starting to get a sense of what might be important.
Bug looked expectantly back and forth between the other two, then slumped slightly when they continued staring at her.
“If the Wanderer took this route, which doesn’t seem like it crosses the river or any big streams that flow into the river, …” She said, expectantly. “Then … ?
It was Cy’s turn to slump.
“Then how did the plague get from him into the water?” He replied. “We must be on the wrong track.”
Luce just kept pushing.
“Maybe, maybe not.” She said. “There’s a lot we still don’t know.”
“But it’s not looking good?” Asked Bug, going back to pushing. “At least, it’s not looking good for the idea that it’s one guy and some bad luck?”
“Ohh, definitely not looking good for that theory.” Luce agreed. “But we can’t say for sure; Maybe there’s a stream or culvert or something around the next bend?”
There wasn’t.
There wasn’t one around the bend after that one either, but as they continued to trudge along the track Cy, who had reclaimed the spot walking ahead, called out.
“We’re here!” He yelled. “And it looks … It looks clear?”

Luce and Bug let the railcart glide to a halt, then rushed forward, Luce putting the brake on she passed by.
Up ahead, the cutting widened slightly into a sort of ledge, then simply stopped a rock wall. The tracks, however, continued through a wide brick-lined archway and vanished into the hillside.
“I was hoping that there’d be a curtain of vines, or bushes in the cliff wall, or … Something.” Cy complained, pointing accusingly at the tunnel. “But it’s just some brickwork; Like a big fireplace or something.”
Bug slowly nodded, looking at the tunnel with her head cocked to one side.
“I was expecting something just carved out of the rock, not a tunnel with this decorative stuff.” She agreed. “And … Is it just me, or is it really wide? It looks wider than it needs to be.”
“And not as dark?” Luce added. “Though I think it’s just wide because of the angle? It’s not going straight into the hill, it’s sort of curving in?”
The trio looked at the tunnel for a while, then walked closer.
“So, a bit of a let-down of a tunnel?” Cy asked. “And I think you’re right, Luce; More light in there than I’d expect for the inside of a hill.”
“If there are weird magical glowing crystals in there, I’m going to be very annoyed.” Muttered Bug. “Not at the crystals or the tunnel; At whoever decided that all those books I read were ‘fiction’.”
“Mister Station would make a good dragon rider or something.” Luce suggested, squinting at the tunnel entrance. “And I’m pretty sure I can see light in there. Not much, but more than there should be. Maybe the hill isn’t that thick?”
They stopped at the entrance, looking in.
Cy made a show of examining the tracks and as far into the tunnel as they could see, then threw up his hands in frustration.
“Absolutely no sign! No idea if the Wanderer came this way!” He bitterly complained. “I’d at least hoped for rocks that had been moved, or a cave-in with a cleared path, or … or something!”
“Not even any convenient footprints in the mud, because it hasn’t rained in forever, no discarded packaging, because that was all back at that station, or anything else.” Bug agreed. “It’s not really our fault that we’re not good at being ‘plucky young adventurers’ from a story, because this valley really isn’t well set up for it.”