Children's animation in which the trains talk, think and don't need drivers. On an icy day, Wilson and Koko go out to sand the tracks in the mountains.
On an icy winter's day, Wilson and Koko are sent out to sand the tracks in the mountains. They take a shortcut through the ice cave. Koko does everything properly, but Wilson doesn't keep his mind on the job, as he has fun exploring. He doesn't realise that an icicle has fallen into his sand wagon, wetting the sand and rendering it useless. He's stuck! He figures out a way to dry the sand by using the heat from his engine and makes it back to the depot - after finishing his job, of course!