Dirty Work is the 39th episode of Thomas and Friends
Diesel, the newest engine on the Island of Sodor, is having a hard time having been made to look silly in front of the trucks, who delight in teasing him. Duck decides that Diesel has gone through enough and stops the trucks from their joking. Diesel is still furious and accuses Duck of making the trucks laugh at him. The big engines are nearby and, knowing that Duck would never do that, tell Diesel so. Henry reminds Diesel that while he, James, and Gordon have some differences with Duck, they would never tell the trucks about them.
By now, Diesel's hatred of Duck has grown to such a point that he wants him to be banished and inspired by the engine's words about trucks, makes a plan, for he will tell lies about Duck. Going into the yard the next day, Diesel tells the trucks that he laughed at the joke about him the day before and tells them some about the bigger engines and claims that he heard them from Duck. Before leaving he tells them not to tell the bigger engines he told them. The trucks find these jokes hilarious and laugh at the bigger engines, and tell them that they came from Duck in order to get revenge on him for forcing them to behave.
Gordon, James and Henry, believing that Duck was the one who told the silly stories about them, hold a meeting and agree that Duck needs to be paid back for teasing them. Later Duck returns to the shed after an extremely hard day's work. However, when he tries to get back inside for a rest, the bigger engines instead wheesh him. They tell him that, after telling tales about them to the trucks, they no longer trust him and want Diesel to replace him. Duck denies this and an argument ensues, but it is not long until the Fat Controller arrives to intervene and see what the commotion is and is told of the bigger engines' accusation against Duck and tries not to laugh. The Fat Controller gives Duck a chance to explain himself and Duck tells the Fat Controller that his only wish at this point is that he had thought of those names himself. Diesel comes forward and when the Fat Controller asks him what he knows, Diesel feigns shock at Duck's actions, but claims ignorance otherwise.
The Fat Controller apologises for the inconvenience to Duck and sends him to work with Edward at Wellsworth Station while he tries to get to the bottom of the incident. Thinking the Fat Controller has turned against him too, Duck, beginning to cry, agrees and puffs away. Diesel smirks, happy with his "victory".
- Sir Topham Hatt