James seems to think diesels are not normal and shouldn't be used, but when a diesel rescues him one cold day he has to admit that they can be useful engines, too.
Duck the saddle-tank engine is Great Western and proud of it! In this book, he laughs as a jealous Gordon loses his dome, meets the oily Diesel Engine who gets him into trouble, and has a close shave before finally saving the day.
A visit from the City of Truro, a famous diesel engine, has Duck feeling proud and Gordon feeling envious, but when a new diesel causes trouble, Duck has to prove himself.