Stepney, a very old engine, is taking the museum cars to the Natural History Museum. James and Henry think that not only is Stepney an old "bucket of bolts," but that the museum cars carry "just a lot of old nonsense." When Stepney breaks down, Thomas doesn't want to get stuck being seen with the old dinosaur bones and relics of the past. What will his friends think, and more important, what will the children say? Thomas is in for a big surprise!