One day in the sheds, Percy is eager to tell a disinterested Gordon and James some news. Both quickly tire of Percy's usual manner and the tank engine tells them that as the work in the yard is getting too hard for him, the Fat Controller is planning to bring a new bigger engine in to help. James is unimpressed, telling Percy that if he worked harder instead of chatting, the yard would be a happier place. Percy then leaves to do his work.
As he works, Percy grumbles to himself that, since he accidentally reversed at a signal, the larger engines now consider him to be a "silly little engine" and often order him about. Percy wants to teach them a lesson, but does not know how to do it. He then works very hard all day and by the afternoon he is worn out. After bringing some express coaches to the station, he sees the Fat Controller on the platform who notes that Percy looks very tired, which Percy confirms. The Fat Controller cheers Percy up by telling him the new engine is bigger than him and can probably manage the work alone. He then asks if Percy he would like to help Thomas and Toby build the new harbor which cheers Percy up straight away.
Soon the new engine arrives. The Fat Controller asks the engine his name and the engine introduces himself as Montague, but tells the Fat Controller he is often called "Duck" due to his supposed waddle, and declares that while he does not believe he has a waddle, he admits to liking Duck better than Montague. With that, the Fat Controller agrees that the new engine will be known as Duck. Percy arrives and the Fat Controller asks Percy to show Duck around.
DuckTakesCharge27 Duck does his work quietly as he brings some coaches to the station, leading Gordon, James and Henry to decide to boss him about like they do to Percy. Gordon and Henry then start to leave the station on either side of Duck, quacking and blowing steam at him. As Percy sees everything and is cross, Duck takes no notice and just wants to wait until the larger engines get tired of their teasing. Duck then asks Percy if the larger engines boss him about and Percy confirms they do. Duck decides to take charge and put a stop to it and tells Percy what they will do.
That afternoon, the Fat Controller sits at his desk looking forward to having toast for tea. Suddenly, he hears a horrible noise coming from the yard and looking out his window, he sees Percy and Duck blocking the turntable and preventing an angry Gordon, James and Henry from entering the sheds. The Fat Controller grabs his hat and rushes to the yard.
At the sheds, Gordon, James and Henry are furiously wheeshing and whistling loudly when the Fat Controller arrives and demands silence before demanding an explanation from Duck and Percy. Duck politely explains that, as a Great Western engine, he prefers to do his work without any fuss, but wants the other engines to know that he and Percy will only take orders from the Fat Controller. As the three larger engines start whistling angrily again, The Fat Controller shouts at them to be quiet. The Fat Controller then tells Duck and Percy that he while he is pleased with their work, he is not happy with their behavior tonight, as they have caused a disturbance. Gordon, Henry and James snicker at Percy and Duck's dilemma, but the Fat Controller turns back to face them and scolds the three larger engines that their actions have been much worse, as they made the disturbance, and then tells them that Duck is quite right that he is the one to give orders, not them. With that, the three engines quickly fall back into line.
Soon Percy is sent to work at the harbor on Thomas' line, leaving Duck to do the work alone, something he manages easily.
- The first appearance is Duck