Spring had come to the Island of Sodor and in the hills, the Narrow Gauge Engines were looking forward to the many visitors coming to their little line.

One day, Duke, one of the oldest engines on the island, was making his first run up to the Blue Mountain Quarry. When he arrived, he noticed a green he had never seen before. "Hullo," he said. "My name is Duke and I have come to help with a load of stone."

"Oh, your trucks will be ready soon. So, you're Duke? Sir Handel and Peter Sam told me all about you. My name's Luke."

"Oh yes, I've heard about you too," said Duke. "It was very brave of you to hide out here for so long."

"Well, I couldn't have done it without the other engines."

Duke's trucks were soon ready. "Skarloey is covering the first passenger train today," he said, "so I was sent to collect the first stone train."

"It must be nice to work on your railway," said Luke. "It must look wonderful in the spring. I've never even left the Quarry since I first arrived."

"I wish I could help."

Then, Luke had an idea. "Maybe you can help me."

"What do you mean?"

"If you do my work here in the quarry, I can help on the rest of the railway."

Duke wasn't sure. "Working on our line is very different from just working here in the Quarry, but I'll see what I can do."

That night at the Depot, Duke spoke to the Thin Controller and the other engines about Luke's idea. "I suppose that could work," said the Thin Controller thoughtfully, "but you all must make sure he knows exactly what to do."

The next morning when Duke arrived at the Quarry, he told Luke about the arrangements. Luke was excited; seeing the rest of the Narrow-Gauge Railway felt like he was on his own holiday. Duke told him as much as he could, and Luke was soon trundling happily away with more stone trucks.

Luke loved seeing the rest of the railway. The sun shone, the birds sang, and the trees rustled in the wind. Everything was so new and exciting to him that his Driver had to check him more than once. "Steady, boy," he laughed. "There's plenty of time."

The other engines were happy to see Luke and so were the passengers. Every time he passed the stations, they smiled and waved at him. The engines did their best to help their friend learn the line. Luke listened as carefully as he could and tried hard to remember everything they told him."

Some days later, Rusty was out inspecting the line. When he reached Sodor Castle, there was trouble. The rails had become worn and bumpy. The little diesel raced back to the last station so his Driver could telephone the Thin Controller.

Later, Luke was getting ready to leave with some picnic supplies for the station. He was just pulling out of the Depot when the warning came through. "Luke!" called Rheneas, "watch the Causeway! There's trouble!"

But Duncan rattled through with his trucks and Luke didn't hear him clearly, nor did his Driver. "Will do!" he called back and hurried away.

Further down the line, a workman was putting up warning signs at the Causeway Junction. Soon, he was called away and later set out to help repair the line, but the workman had accidentally forgotten about the last warning sign. It sat in the middle of the junction and didn't show which line was under repair.

Luke was enjoying himself, but then he saw the warning signs at the Junction, but he didn't know what they meant. "Rheneas must have been warning us about repairs," said his Driver, "but what exactly?"

Luke tried to remember. "I think he said 'take the Causeway. It's quicker.'" So, Luke set off toward Sodor Castle, unaware of the danger ahead.

Rusty and the workmen had removed the damaged section and were laying new sleepers when they heard Luke's whistle. "Roasting radiators!" cried Rusty. He sounded his horn as loudly as he could. "Luke, stop! The track is closed!"

Luke jumped as he rounded the bend. "Oh my!" His Driver applied the brakes, and the workmen ran for safety, but it was too late. Luke's wheels left the rails, and he shook, rattled and jolted as they ground the rocks and ballast.

Luckily, no one was hurt.

"What are you doing here, Luke?" Rusty asked. "This line is under repair. Didn't you see or hear the warnings?"

Luke looked ashamed. "I did. I tried to remember what I was told, and I saw the signs at the junction, but I didn't know what they meant."

Luke was soon back on the rails and Peter Sam helped him back to the Depot. Luke was sure the Thin Controller would be cross with him when he arrived that night. "I'm sorry, Sir."

But the Thin Controller wasn't cross. "Luke, you have nothing to be sorry for. What happened today wasn't your fault. Rheneas and Rusty told me everything. Duncan was being too noisy, and the warning signs hadn't been placed properly. From what I have seen, and heard, you have done very well in helping with our spring preparations. You are a Really Useful Engine."

"I couldn't have said it better myself," said a voice and Duke puffed in with another load of stone. "How are you enjoying your holiday, Luke?"

"It's been fun," said Luke, "but…can I go back to the Quarry tomorrow? I'm feeling a little homesick."

And everyone laughed.

Luke was happy to get back to the hustle and bustle of the Blue Mountain Quarry. There is no place he would spend most of his time, but he is always happy to help elsewhere on the Narrow-Gauge Railway when needed and the other engines are always happy to let him see the rest of his home in the hills of Sodor.