Charley McChooChoo is a little switch engine with big dreams. Charley longs for his own train and his own adventure, but Mr. Big doesn't think he is ready. One day, Charley gets the chance to prove himself, but he runs into some unexpected dilemmas along the way.

A new steam engine has arrived on the Chugga Valley Railroad. His name is Willy Whistler, and he has a disability. This means he has a minor problem. He cannot speak; he can only whistle. All of the engines are friendly to him, except Danny Diesely, who calls him "useless" because of his disability. But when Danny gets into trouble, Willy saves the day and helps him get his passengers delivered on time. In the end, Danny realizes that Willy's disability is really an ability, and the two become friends. Indeed, even though Willy has a disability, he is a very helpful engine