The coastline of southwestern Cornwall is dotted with the ruins of old engine houses. Long ago, tin was found in long veins running deep under the ground, and mines were built to exploit this natural resource. The problem is, Cornwall has a high water table, and as such the mines were prone to flooding. As such, stationary steam engines were built to both carry the miners in and out of the mines, and also to pump the water out of the cavern system.

However, the life of a tin miner was always a volatile one, as tin seams are fickle. Once a seam ran out, the mine usuall moved on. The miners moved to a new seam, taking all of their equipment with them- including the stationary steam engines. The buildings, however, were rarely taken with the mining company, and once all the valuables were removed were simply left- after all, there would be plenty of stone available with which to build another engine house at the new location.

One such structure stood in the hills overlooking Perranwell. It had served a mine that had ceased operations in the 1930s, and ever since had stood lonely, like a sentinel standing guard over the valley. Many legends had grown up about it, with rumours that it was haunted by the ghosts of the men who had once worked the machines it had contained.

And then, one day, the fortunes of the Fal River Valley would change again. A rich tin seam was found in the old mine, one which could be exploited economically. As the tin price was very good, the decision was made to try and reopen the mine as a drift mine, though a pumping engine would still be needed.

As such, Perranwell freight yard became the railhead for the construction efforts. The railway moved equipment in and shipped waste rock out to be dumped in an old clay pit. One morning, Brookes arrived from Truro with a train loaded with fresh building materials.

He saw a long train loaded with rock. "That's a lot of waste rock," he commented.

"All of it's coming out of the mine," Porter explained, as he moved some fresh trucks into the sidings. "You'd best get that lot pushed into place as quickly as we can. The owner of the private siding has jacked up his access fees in response to this new work."

"Talk about trying to make a quick buck," Argyle said, as he set Brookes to work. "You know, I can't help but question the wisdom of reopening the seam."

"Why?" Izzy asked. "It brings in loads of employment!"

"Because the land is absolutely criss crossed with unstable tunnels," Argyle explained. "And they won't have had any maintenance done on them in about 90 years. If they're not going through all the tunnels to prop them up, one might collapse. And that would not be a pretty sight."

"Saw the after effects of a mine collapse once," Brookes said. "It was not a pretty sight."

As Brookes' train was unloaded, one of the pieces of machinery looked very odd. It sat on a belt of sorts, with a large saw mounted sideways.

"Excellent!" said one of the miners. "I was looking forward to this arriving!"

"What is it?" Brookes asked.

"It's a rock saw," he explained. "The teeth are made of diamond, the hardest element known to man. It cuts through the rock like butter, and avoids damaging the tin lode in the way conventional explosives would. We'll get it moved into the mine and give it a field test tomorrow!"

The next day, the mine went into full operation, and this meant that tin ore needed moving. Tin ore contains a lot of useless impurities such as arsenic, and as such the rock needed to be moved to a dedicated mill near Penzance to be processed until the stamping mill in Truro was finished. Based on how the men loading the trains were talking, the new saw was working very well.

"It can easily do the work of twenty men!" said one. "Saves us a lot of legwork, that's for sure!"

But nobody thought about other effects it could be having. That night, the rain came, and the workers went home for the night. Brookes was being coupled to the last train heading for the junction when he looked up at the old engine house that overlooked the mine. For a split second, he could have sworn he heard a voice. But he couldn't make out what it was saying.

Suddenly, a huge piece of rock landed next to the track. "Looks like the rain loosened some rock," said Argyle. "We'd best be getting on our way."

Brookes looked up, worried. "What if somebody doesn't want us to be here?" he asked.

"Just my luck," Allura growled. "I thought I'd finally found a place I could plan in peace, and now those noisy workmen start up a mine right next to me. I've already gotten sick of hearing all the work songs."

"They are in rather fine voice," Alfred said.

"Don't take their side," Allura said. "If we get caught, that compromises our chances of being able to escape. And neither of us wants that. We'll just have to hope they don't break through to our cavern."

The next morning, Izzy was out having a stroll around Perranwell. The local area had become incredibly busy thanks to all the mining, and as a result tourism had taken a small backseat apart from people coming to watch the mine workings.

Izzy whistled happily as she walked along. "Couldn't be better!" she said with a smile. Just then, she spotted a strange cavern jutting out of the mountainside, not far from the mine. "Hey, that cave looks fun!" she said. "Mom and dad would love to explore that, I bet. Such a shame he's off at the oil rig right now." She shrugged. "I'll take the needed precautions."

She quickly produced her caving gear from nowhere, securing a helmet, light, harness, and battery pack in place before proceeding into the cavern. "Hello? Is anybody there?"

She heard a noise in response. "Hmmm. Maybe I should get them a welcome basket!"

Sunny looked up from her stand in the town square. "Here's a fresh load to go to the mine!" she said, to a waiting workman.

"Thank you," the workman said. "Your drinks really are helping to keep the men hydrated."

"Just be sure to keep them refridgerated until you need to drink them," Sunny reminded him.

Izzy suddenly appeared. "Hi Sunny! There's somebody new to the area in Perranwell. Could you rustle up a welcome basket, please?"

Sunny quickly dropped some fruit into a basket. "Here you go! Enjoy!"

Izzy sped off as Pipp and Zipp lined up for a drink. "What was that about?" Pipp asked.

"Something about somebody being new to town," Sunny said. "Sometimes Izzy is just Izzy."

Izzy walked back into the cave, listening to two figures speaking. "You know, Alfred, there is one thing I really like about this place."

"And what is that?"

"No annoying people. Especially not that irritating girl who foiled our plans in Chicago."

Izzy stopped. "Hi new friend! I got some stu..."

Her voice trailed off as she saw Allura walk to towards her. "Wait, Allura?"

"As if ruining my plans wasn't enough, you come to gloat about it in my face," Allura growled. "I've had quite enough of your face and your irritating voice for one day."

"Couldn't we be friends? Maybe I could help you!"

Allura narrowed her eyes. "I don't need your help. I don't want your help." Her eyes started to glow. "Now get out."

Izzy suddenly found herself outdoors again. "Hey, what was I doing again?" she asked, before suddenly spotting the cave and hearing somebody speaking. "Hmmm. Maybe I should get them a welcome basket!"

Sunny was incredibly confused when Izzy suddenly asked for her another welcome basket. And another. And another. And another. "I'll have run out of bananas at this rate!"

Sunny wasn't the only one incredibly confused. Allura was baffled, then increasingly annoyed that Izzy kept coming back with more and more baskets loaded with fruit. The pile of baskets grew taller and taller until it almost reached the ceiling.

When Izzy next returned to Falmouth, Sunny already had a basket ready for her. "Let me guess, new friend?"

"Where are you taking all these baskets?" Zipp asked.

"Oh, to a cave near the mine workings at Perranwell!" Izzy said. "Somebody is living in there now, so I want to say hi!"

Zipp looked at Pipp. "I wonder if that's the cave we got stuck in when looking for the Ocean Lily."

"Could be."

Sunny suddenly had a look of realisation on her face. "Hang on a moment. Izzy, does the cave have rails running into it?"

"Yeah! Makes it really easy to find!" Before they could say anything else, Izzy was off on her way again.

Sunny looked at Zipp. "Remember that mystery engine we found prowling around Perranwell?" she said.

"Yeah?"

"What if he lives in that cave?"

"We need to follow her, and fast," Pipp said.

Izzy looked on in confusion at the enormous pile of fruit baskets in the cave. "Has somebody been doing regular fruit deliveries here?"

"You, you utter annoyance," Allura growled, appearing in front of Izzy. "I've had quite enough of your antics, Izzy Moonbow."

Izzy looked confused. "Only people who know me call me Izzy. If they don't know me they usually call me Isabelle given that's what written on my birth certificate."

"But I know you well, you annoying child. But I can't have you blabbing about this place, and seeing as wiping your memory over and over again doesn't work I'll have to resort to more... drastic measures."

"I like the sound of this," Alfred said.

Izzy tried to run, but her boots couldn't gain traction on the icy ground as some sort of snowglobe formed around her.

Allura turned around and relaxed. "The poor fool doesn't realise it's soundproofed in there. Nobody can hear a word she's saying."

"Will you let her out?" Alfred said.

"Of course. But this should scare her so badly she'll never come here again."

"Hey!" shouted a voice. "Let her go!"

Allura smiled. "You should be glad we're on top of granite here so I can't just drop her through the floor."

Zipp and Pipp charged at Allura, who fired off an energy blast that shook the caverns. Ice crystals began to drop from the roof and slam into the ground below.

The two sisters rolled behind a rock to block Allura from their view, and then moved over. "Sunny, you're up!"

Sunny dashed into position, and ponied up before firing a single blast at Izzy's prison, blowing it open. "There! You're free!"

Izzy needed no prompting, and ran for the cave exit whilst Allura jumped onto Alfred's footplate. "We need to find a new base. But before we go let's give them a little distraction!"

Suddenly, at the mine, warning klaxons started to sound as a voice began to sound over speakers. "WARNING. WARNING. GROUND SUBSIDENCE EXCEEDING SAFE LIMITS. ABANDON MINE AREA AND PROCEED TO REFUGE ZONES IMMEDIATELY. WARNING. WARNING. GROUND SUBSIDENCE EXCEEDING SAFE LIMITS. ABANDON MINE AREA AND PROCEED TO REFUGE ZONES IMMEDIATELY."

Brookes, who had brought some trucks up to be loaded, looked over in alarm. "That's not good."

Argyle looked over from the trucks and saw something appearing before them. "How did that boulder get there?"

Sitting on front of them was an enormous boulder made of ice. And then it started to roll towards them.

Argyle leaped into the cab and released Brookes' brakes before opening the regulator as far as he could. Brookes shot backwards down the line as the boulder followed.

Brookes reversed into a siding. "Let's wait here until the boulder goes by!" he said. But the boulder was nowhere to be seen.

Suddenly-

"THE BOULDER'S BEHIND US!" Argyle shouted. "FORWARD, QUICKLY!"

Brookes shot forward as the boulder appeared behind them. There was something off about this boulder. It seemed to be chasing them. Hunting them. As if it had a mind of its own.

Brookes hammered into a siding near the mine workings as the boulder roared by, before it suddenly changed directions and began rolling back towards Falmouth.

"We need to warn other engines on the line!" Brookes said.

"Yes, but how?" Argyle said. Just then, he had an idea. "The signalman!"

Further down the line, Alexandra was making her way up to Perranwell when there was a buzz. "What's that?" she asked.

Lord Haven listened. "Warning signal. Runaway rolling stock, find shelter immediately."

Just then, the rumbling grew louder. And both railmotor and driver saw the enormous ice boulder moving towards them! "Back, back, quickly!" Alexandra shouted.

Lord Haven jammed Alexandra's cutoff into reverse and opened the regulator, running downhill as fast as he could. The boulder had arrived so suddenly he'd had no time to change cabs, and had to stick his head out of the window to see where he was going.

As they rocketed towards Penrhyn, Lord Haven sounded the whistle six times- which indicated he wanted the cattle dock siding. The signalman threw the points and they rocketed into the siding as the boulder thundered by.

As Alexandra stopped, Lord Haven's radio buzzed. "Hello?"

"Did a giant boulder just pass you?"

"Yes, why?"

"We need to warn all trains in the system. Are you aware of any other trains on the line?"

"Harvey was supposed to bringing some extra trucks up to the mine, and-"

"What's his radio frequency?"

Harvey was waiting for his stock to be readied at Penmere when he heard a sudden rumbling noise in front of him. "What's that?" he asked.

Goldie then heard the cab radio buzzing, and grabbed it. "Hello?"

"Goldie, get Harvey off the main line now! A siding, anywhere, just off the main!"

Goldie then looked out of the cab and saw an enormous ice boulder rolling their way. "Oh crap." She put Harvey into reverse and backed him into the fuel depot as quickly as she could, before the boulder hammered by.

"If that thing crashes into Falmouth, they're doomed!" Harvey shouted.

Just then, Goldie saw something familiar fly through the sky past them. "Sunny!"

Sunny was chasing the boulder as quickly as she could. She was getting closer, but they were running out of time. But sure enough, she caught up with the boulder, and with a mighty blast of energy blew it to pieces. The fragments flew through the air and landed in the ocean nearby, well clear of any buildings.

When news of the accident reached the mining company, they decided to close the mine. "Nature," said one of the directors, "has a way of reminding man just how insignificant he truly is. We should have left this part of the land alone."

Now the mine sits silent and still, the old engine house once more watching over a silent valley. And of Allura? Well, I'm afraid that's a story for another time.

Author's Note

This chapter combines the plotline of the Thomas and Friends episode Rusty and the Boulder with the Tell your Tale short Oooh, a new Friend! These two episodes, to my surprise, went very well together, and given I had previously adapted the former it only felt natural to adapt a classic episode once again.