One day, BoCo is shunting by the quayside when Ten Cents arrives. Ten Cents is currently filling in for a barge that is yet to arrive. He explains to BoCo that he hasn't had any contracts lately and is feeling unwanted. BoCo says he has had a similar experience, and recounts the story.
BoCo and D199 are resting in their shed on the Other Railway when Sir Charles Topham Hatt arrives and explains that he needs a diesel to help Edward on the Brendam Branch Line. He is initially here to see D199, but after witnessing his snobbish opinions on steam engine he turns to BoCo. BoCo says he would be honored, but he does have a tenancy to break down often, due to being a new experimental diesel engine design. Sir Charles accepts this, and has a meeting with the foreman.
BoCo arrives on the island next day and is introduced to Edward, who tells him that his china clay train is waiting at the harbour. BoCo goes to collect them, but there is no engine in sight. As he leaves with the train he thought was his, he hears a faint whistle in the distance. When he arrives at the yard, a yellow saddle tank engine appears beside him. BoCo mistakes the engine for a troublemaker, and tells him to go away. Bill and Ben play their trick on BoCo, whom discovers that there are two engines. Edward arrives and sorts out the confusion.
BoCo takes his train over Gordon's Hill, his engine almost giving out, but he makes it to Maron on time. He has to shunt his train off the main line so Henry can pass. Henry arrives and BoCo explains about his engine faults. To his surprise, Henry is sympathetic and somewhat relates to his experience. As he leaves, he remembers something that Sir Charles told him; "Mechanical faults can be rectified. Number 3 is proof of that".
BoCo finishes the story, and Ten Cents goes to tow The Capaldi into dock. BoCo takes his train along to Crock's Scrap Yard, where he overhears a group of workmen talking about not using the boat contract for exporting the metal, although Ten Cents will become of use. BoCo thinks they want to scrap him.
- Bill and Ben
- Ten Cents
- Sir Charles Topham Hatt
- Sheffield (does not speak)
- Donald (cameo)
- Other Railway Diesels (cameo)
- Trevor (cameo)
- Gordon (indirectly mentioned)
- WildNorWester as the Narrator and Sir Charles Topham Hatt
- EpicThomasFan713 as Edward
- Bourbon-BobJimmy as Henry
- TheHappyTruckShunter as Jinty
- Lady TehPikachu as Bill and Ben
- SmudgersPKMN as BoCo
- Thomas1Edward2Henry3 as D199
- Geebmachine as Ten Cents
- The episode is an extended version of the Railway Series story "The Diseasel", from BoCo's point of view. Also referenced are The Flying Kipper and Edward and Gordon.
- The boat "The Capaldi" is a reference to Doctor Who's 12th Doctor. Another ship is named "The McGann", a reference to the 8th Doctor.
- This is the first appearance of Jinty in the series and D199's first appearance since the first season of Sodor: The Early Years.
- TheHappyTruckShunter joins the voice cast.
- This is the first episode to have Henry voiced by Bourbon-BobJimmy, BoCo voiced by SmudgersPKMN and D199 voiced by Thomas1Edward2Henry3.
- It was established in Medivac that Donald and Douglas chose to be painted blue after they saved some Scottish railfans and were given a new coat of paint as a reward, which takes place in 1984. However, in this episode, (taking place 1965), Donald was already painted blue.