Air date: October 20th, 2003 (UK), February 23rd, 2004 (US)
Donald and Douglas enjoy working on Sodor, but sometimes they long to return to Scotland. One day, they arrive at Brendam Docks, where the Fat Controller tells them that Lord Callan is reopening his castle. The twins are to take banners and bunting to the castle for the celebrations. Donald and Douglas are excited as going to the Scottish castle would be like going home. Harvey tells Percy that the celebrations will be near Castle Loch, which worries Percy. Douglas teases Percy by saying the monster who supposedly lives in the loch might catch him, but Donald doesn't think there is a monster in there.
The twins take their train along the line and spot the castle in the distance, but they have to stop suddenly to avoid hitting a tree that has fallen across their track. Then to make matters worse, a landslide behind them knocks the brake van off the rails, leaving the twins stranded. Douglas' driver calls the Fat Controller, who promises to send help as soon as possible.
But by nightfall, no help has arrived. Suddenly, the twins see a very strange shape coming towards them through the mist. Douglas thinks it is the monster, but as it reaches them, the shape turns out to be Harvey pushing the breakdown train. Donald and Douglas are very relieved.
By morning the tracks are clear, and Donald and Douglas make their way to the castle. Lord Callan and the Fat Controller both call them very splendid and useful engines, to which the twins heartily agree.
This episode contains examples of:
- Argument of Contradictions: The twins argue about a monster:Douglas: There's no monster!
Donald: There is too!
Douglas: There is not!
Donald: Is too!
Douglas: Is not!
Donald: Is too! - Not the Nessie: When Donald and Douglas get trapped by a landslide and a fallen tree, they have no choice but to spend the night where they are until help comes. On that night, the twins see what looks like the Loch Ness Monster coming towards them in the mist. Fortunately for them, it was just Harvey pushing the breakdown crane, and their arms gave them the appearance of the Monster's head and tail.
- Stock Footage: This episode begins with footage of Donald and Douglas pulling a goods train across the viaduct as Sir Topham Hatt watches from a distance from "Twin Trouble".
