The team must build a miniature train ferry at the Caledonian Canal, and cross a 12-metre span at Loch Lochy. It's not easy... And then the little train sets off on its epic journey across Scotland.

The tiny train ferry crossing doesn't go well, and the team also have to build a huge viaduct. The train is making slow progress, with much more rugged terrain still to come...

The tiny train grinds to a halt on its first gentle hill, but one of the team has a brainwave. And the build team decide to construct an ambitious curving trestle bridge to cross a rocky stream.

From viaducts to hills and fatigue, the teams face a series of tricky challenges on one key day. And Dick upsets the train team by deciding to replace the tiny steam train with an electric one.

It's the last stage of the tiny train's epic journey. She's in bad shape and still has to face bad weather, rocky terrain and the steepest part of the route before she can reach Inverness.