The Other Side of the Mountain.Thomas wants to find out what is on the other side of a mountain on his branch line, when Bertie tells him about the experience and sights he sees on that side. This makes Thomas intrigued, and he wants to see for himself; but knows he can't do it. One day when he has to deliver a goods train, he rushes by Bertie who desperately tries to explain the truth after their argument the day before. Thomas suddenly derails by missing a signal and the Troublesome Trucks pushing him and goes so far as the other side through a forest. When Butch is tasked to take him back by road, Thomas is more disappointed when he can't see any of the sights that Bertie was talking about. Then he understands what Bertie meant when he sees a poster, of a jungle with a river and a rainbow, and Butch and Thomas laughs as they continue back to the other side, and at the Steamworks, he apologizes to Bertie for misunderstanding him.