After a storm causes a rockslide in Crumble Canyon, Ashima is eager to clean and clear the chaos with her new friends. However, Thomas and the others are concerned if Ashima were to help them, the mucky mess could ruin her beautiful paint.
While Bruno helps Diesel with a heavy delivery, Diesel fails to listen to his advice, causing them both to get stuck in Crumble Canyon. Now it's up to the two of them to listen to each other to find a way out and complete their delivery.
When aging Toby comes to Knapford, he struggles to keep up with all the young engines. He still has a lot of zip in him, but around all these modern engines, he loses his confidence.
After Salty the Diesel Engine returns from his worldly travels, he sings a shanty to Thomas and Percy about a legendary treasure lost on the island of Sodor; the two friends are eager to see if the legend is true.
When Nia suggests adding a song to spice up Sir Topham Hatt's new bench unveiling, he calls upon her to write a song for the ceremony, but it'll take some brainstorming to discover what's special about a plain bench.