All of the Fat Controller's engines are useful in different ways. Gordon is a good at being an Express engine, Percy is good at taking the mail and Edward is good at being a back engine. When engines like James have heavy goods trains to pull up Gordon's hill, Edward will buffer up behind and push. But Edward is old and some engines think this makes him unreliable.
One morning, Gordon is snooty. He comments that Edward is a "useless old steam-pot" who should be retired. Percy is confused because Edward doesn't have tyres. Thomas explains that retired means to be taken out of service. "And not a moment too soon" says Gordon. Henry and James, the sheep, agree with Gordon, their leader, but Percy is upset because he is his friend.
Later, Percy's driver asks him why he looks so sad. Percy tells him that the big engines don't think Edward is useful anymore. At the station, Percy's driver saw the Fat Controller and told him what Percy had said. The Fat Controller promises to attend to the matter immediately. He concocts a plan.
He sees Edward and tells him that the new branch line is complete and he wants him to help Stepney to run it. Edward is worried because nobody will be able to take his trucks. The Fat Controller reassures him that Duck will do his work.
How will this help you might be asking. Well...
The other engines are pleased that Duck will be helping them. They believe he is very reliable. Gordon, however, is so proud today that he boasts he doesn't need a back engine (when pigs fly) and he puffs away with a heavy express.
Edward is having great fun with Stepney delivering passengers to the stations and enjoying the countryside. Duck, however is unhappy. He does not have Edward's ability to make the trucks behave and they are playing tricks on him. They taunt "Duck should play with other ducks coz he's no good at pulling trucks! Quack! Quack! Hold back! Hold Back!" Poor Duck reaches Gordon's hill and feels himself going slower and slower and comes to a complete stop halfway up the hill. His guard telephones the signal man to switch Gordon to the other line but alas, it is too late. He advises that the guard flags him down instead. Gordon sees the red flag and complains that if stops on the hill he will never get started. He buffers up to Duck and trys to move but can't. His driver says they need a back engine and he sends for Edward. Gordon was cross.
Edward is excited because he will now be the back engine for two trains. He buffers up and the strange train sets off. They arrived at the station and a boy comments that the back engine must be the strongest and the best. Gordon is embaressed. To make matters worse, The Fat Controller reprimands Gordon for being rude about Edward. He says that he has proved to be useful, reliable and very helpful. Gordon is ashamed.
Next morning, Gordon apologises to Edward and thanks him for helping. Edward is pleased. The Fat Controller's plan had worked. There was no more talk about Edward retiring.