"I'm Great Western and I..." "Quack, quack, quack!" "What?" "Ye heard, 'Quack, quack' ye go! Sounds like ye had an egg laid! Now wheesht and let an engine sleep!" "Quack yourself!"
— Donald and Duck
Duck and Donald is the seventeenth episode of the Engine Friends miniseries.
Duck, the Great Western Engine, works very hard on the Island of Sodor fetching coaches and trucks for the other engines. He always does the work quickly and without complaint. One day, the Fat Controller comes to see Duck in his shed, thanking him for all the hard work he has done and asks him if he would like to have his own branch line. Duck happily accepts.
Taking charge of his new line, Duck is happy at being given such a big responsibility. He finds that it runs along the coast and into a port where ships dock. Duck very much enjoys exploring the new line as well as being close to the sea, remarking that it is just like being on holiday and is soon busier than ever before. The Fat Controller is building Duck a station at the port, and as Duck helps out with the construction, Bertie looks after Duck's passengers while the other engines also help. However it is a long job, but thanks to everyone helping the station will be finished on time.
Duck is still feeling the importance of his new responsibilities, and enjoys talking about them. One night in the shed, he starts telling Donald how important he is to the line now. Donald is sleepy, but when Duck carries on Donald accuses him of quacking like a duck to the point that he sounds like he was going to lay an egg. Duck is very angry about this, and tells his crew the next day. Duck's fireman has a plan to pay Donald back, and he tells Duck and the driver. They all agree, however soon Duck is back at work and nothing else is said. However that night when Donald goes to sleep, Duck's driver and fireman drop something into the Scottish engine's water tank.
The next morning when Donald stops for water, his crew are astounded when a white duckling pops out of his tank. Donald sees the funny side of the joke, and the duckling is friendly towards him and the crew and is allowed to ride in his tender despite the other engines often teasing him. The duckling soon tires of travelling and hops off at a station which is where she would end up staying.
That night, Donald's crew decides to pay Duck back and the next morning the driver and fireman find a nest with an egg in under the Great Western Engine's bunker. Donald jokes that Duck must have laid it in the night, and Duck agrees that Donald has won.
The duckling enjoys swimming and playing in a pond near her station where she can see the engines going past. The stationmaster calls her Dilly, but to everyone else she will always be Donald's duck.