After leaving San Francisco, Thomas and Sam continued their journey north. Gradually, Sam had to stop. "I'm afraid this is where our trip ends, Thomas," he said. "You'll be on your own for a while, but it won't be long."

"Where are we going next?" Thomas asked his Driver.

"Canada, and we're due to stop after passing through the Rocky Mountains?"

"What are they?"

"From what I've heard," replied Sam, "They're very tall mountains; so high that there's always snow on them, even in the summer."

"We're only stopping for coal until we reach the other side," added the Driver, "so you'll need a snowplough and extra water before we continue."

In the yard, Thomas had a snowplough fitted to his front. He took on water and lots of coal and collected some water tankers. After saying 'goodbye' and 'thank you' to Sam, Thomas left for Canada alone.

It was a long journey to the Rocky Mountains. The only times Thomas ever stopped was to rest, collect more coal or take on water. At last, Thomas saw a large mountain range ahead. Those must be the Rocky Mountains, he thought, and they were.

As they trundled along, they passed through thick groves of trees. "Wow," gasped Thomas, "I've never seen trees as big as these before."

"This is the Redwood Forest," said his Driver, "and these trees are very special. Their wood has a red colour and they have been around for a very long time."

"I can't wait to tell Henry about this."

They also passed by some very big lakes, and they too were bigger than any Thomas had ever seen. "It's like looking in a giant mirror," he puffed.

"This water is very clean," his Driver explained. "That's why they use it for drinking."

The Mountains were very big as well and Thomas began to climb. As he puffed higher and higher, the tracks became steeper and steeper. As they rounded a bend, Thomas looked down. "Bust my buffers," he said nervously. They were very high indeed.

Soon, it became colder, and it started to snow. There were only a few flakes at first, but the snow got heavier and heavier as they carried on. It wasn't long before the snow started to pile on the tracks.

For once, Thomas was glad he had a snowplough, but the snow piled higher, and the drifts became thicker. Even with a snowplough and plenty of sand, Thomas was starting to struggle.

Then there was trouble.

The snow had packed in so tight, Thomas finally stalled with spinning wheels. "Cinders and ashes," panted Thomas. "There's too much snow. I can't get through."

"Botheration," said the Fireman, "We're stuck."

Suddenly, they all heard a strange noise. Thomas' Driver looked back. "I can see a light," he said. "I think help has already arrived."

As the light grew brighter, the strange noise got louder. To Thomas, it sounded like a big, roaring monster, but also…familiar.

At last, the big thing rolled alongside Thomas and the snow flew everywhere. Then, the noise became quieter, and Thomas saw who their rescuer was; it was a big engine with a very big snowplough. "Hello, I believe you're Thomas. I can see you're having a little trouble with the snow. My name is Marshall, and this is my rotary snowplow."

"Fizzling fireboxes! That's a big plough."

"I know, I get that a lot." Marshall observed the situation. "Now, if you back up a little, you can switch tracks and I can help you finish your journey."

Thomas did so. He watched as Marshall shoved his snowplough against the big drift and the snow flew aside on the wind. Thomas was impressed.

"How are you doing back there?!" shouted Marshall.

"Fine, thanks to you," whistled Thomas. "I've only ever seen one snow-clearing engine before."

"Is that so? Well, we rotary snowplows were invented right here in Canada especially for clearing heavy Canadian snow."

The two engines continued their journey through the Rocky Mountains and as the sun went down, they reached the next station. Everyone cheered for Thomas and Marshall and the two engines made their way to the yard to rest.

"Hello, Thomas!" Thomas jumped. "It's nice to see you again."

Thomas could hardly believe it. "Dustin?! what are you doing here?! I thought you lived in the United States."

"I do, but this snow has been causing so much trouble, they asked me to help. I sometimes do and I couldn't let my friend, Marshall, struggle with all the work alone."

"We certainly didn't expect as much snow as this," added Marshall. "When we heard you were coming, Dustin told me about you and when the weather got worse, I volunteered to go and help you."

"And I'm glad you did," said Thomas. "Thank you."

"It was no trouble at all. I know these mountain tracks like the back of my plow."

"So, Thomas, what has happened since I left the Island of Sodor?" Dustin asked.

After his long day out in the snow and being rescued by Marshall, Thomas was more than happy to talk with his friends, old and new, and Dustin and Marshall were happy to listen.