It was a bright autumn morning on the Island of Sodor. Gordon had just arrived at Knapford to collect the Express. Suddenly, he jumped when a big silver engine seemed to appear alongside him. "What?! Where did you come from?" he cried.

"Oh, did I scare you? So sorry," the engine replied. "Sometimes I can't help it. I'm the best hider ever, you know. Watch…INVISABILITY OOOON!"

A big cloud of steam swirled around the engine and when it cleared, he was gone. At that moment, James departed from another platform and there was the engine again, with his eyes closed. Gordon was surprised…and confused. "What is going on?"

The engine opened his eyes. "Hullo, again."

Just then, the Fat Controller arrived. "Merlin, what are you doing here?"

"I was making a delivery of steel to…um…Brendam Docks. Everyone seemed very busy, so I offered to bring some trucks here to Nap-afford."

"Yes, uh, that's 'Knapford,' Merlin."

"That's what I said."

As Merlin switched back to Platform 2, Gordon eyed the engine curiously. "Well, Merlin," the Fat Controller continued, "I'm afraid you'll have to wait until Gordon leaves with the Express before you can go."

"No problem at all, Sir," grinned Merlin.

When the Fat Controller left, Gordon spoke up. "So, you're that invisible engine everyone was talking about."

"Oh, yes. And it's a pleasure to meet you, Gordon. I heard you're a strong, fast express engine. I am Merlin the Experimental Prototype King Aurthur Class Stealth Engine."

"Aren't you an express engine too?"

"I used to pull expresses on the Mainland, but I can do all kinds of work. These days, I usually make deliveries from the Steelworks where I live." Gordon sniffed as the Guard blew his whistle and waved his flag. "Goodbye, Gordon," Merlin called. "It was nice talking to you." But Gordon wasn't impressed.

Later that day, Gordon met James at Abby Station. "Hullo, Gordon. I saw Merlin here earlier. Did you get to see him this time?"

"Yes, I saw him," mumbled Gordon, "and I must say that I was not satisfied."

James was puzzled. "What do you mean? He's fun, silly and very friendly."

"He's also an express engine. I know express engines when I see them and he is a disgrace; three funnels, red wheels with silver paint and he has no sense of dignity."

James was cross. "Need I remind you that he and his friends rescued Thomas and I from that Steelworks? What about Hank? He's an express engine, but he helps Henry, Murdoch and Hiro with heavy goods. Stanley has silver paint with red wheels too and that's never bothered you."

"Hank is still dignified in his own way and Stanley is only a tank engine. Even without a dome, the City of Truro had a sense of dignity about him. If an engine like me looked and acted as silly as him, what would everyone else think?"

"If it was your choice, we would support you," retorted James. "Even if he wasn't dignified, Merlin would be just as reliable as any of us." And he fumed away.

The next day, it was Rebecca's turn to take the Express. She was enjoying herself as she raced along the Main Line singing a little song.

"Pulling the Express along,

Pulling the Express along,

Pulling the Express along.

We're coming through!"

She had just approached Wellsworth when there was a 'crack' and steam began hissing from her side. "Oh no, what's happening?!"

Luckily, Rebecca managed to stop gently at the platform and while the passengers were bustling about, her Driver looked her over. "Well, that's torn it," he said at last. "One of your steam pipes has cracked. We can't carry on alone, and there's no one to help us."

"Did someone say 'help'?" Rebecca and her Driver jumped and there, beside them, was Merlin. "Oh, sorry, Rebecca, but what seems to be the problem here?"

"Merlin, just in time," replied the Driver. "Where are you going?"

"Back home, Sir. Why?"

"Rebecca's run into some trouble and she can't pull the Express on her own. Can you help us to Vicarstown?"

Merlin smiled. "Of course I can," he whistled. "Passengers are urgent, you know, and we can't let them down."

Merlin switched tracks and buffered up in front. "Thank you, Merlin," wheezed Rebecca gratefully.

"No trouble, my dear. It wouldn't do to leave you stranded."

When everything was ready, Merlin and Rebecca whistled bravely, and the Express set off again. The two engines crossed Gordon's Hill quickly and were soon coasting along the line with the wind whistling past.

Gordon was waiting at Vicarstown. He knew Rebecca would be arriving with the Express soon. Then, he heard two loud whistles and there was Rebecca and the Express with Merlin leading the way. "What in the world...?"

The Express glided into the Station ten minutes early and came to a gentle stop. All the passengers got off and cheered and so did the Guard. "Hurray for Merlin!" they called.

"What is the meaning of this?" Gordon bellowed.

"Isn't it obvious?" a well-known voice replied. It was the Fat Controller. "I was on the Express and I saw and heard everything. Rebecca's steampipe burst, but luckily, Merlin happened to be passing by on his way home. If it wasn't for him, there would have been more confusion and even delay."

Gordon felt silly. "Thank you for helping, Merlin," he said.

"Well, passengers are important after all," Merlin replied.

"I'm sorry if I was rude."

"Don't worry. I may not be as serious as you, but I still know what to do when there's trouble."

Gordon was surprised. "How did…"

"James told me everything. No matter. It just goes to show that even we experimental engines can be full of surprises. Besides, even if we can't do something, we can still try."

"Quite right," the Fat Controller agreed. "Well done, Merlin."

"Yes! well done!" whistled Gordon and Rebecca together and as their whistling was drowned in the passengers' cheers, Merlin could only smile.