The Diseasel

"It's a what'll?" "A Diseasel, I think. There's a notice about them in our shed." "Coughs and sneezles spread Diseasels!" "You had a cough in your smokebox yesterday! It's your fault the Diseasel came!" "It isn't!" "It is!"

- Bill and Ben

The Diseasel is the twenty-first episode of the second season. In the US it first aired on the Shining Time Station episode, Double Trouble.

Plot
Bill and Ben are tank engine twins who work at a china clay quarry. Their jobs are to take the china clay in trucks along the main line for engines and ships.

One day, Bill and Ben arrange some trucks and leave to pick up more, but return to find them gone. Their drivers find a patch of oil on the ground and realise a Diesel is responsible for taking the trucks. Mishearing this as "diseasel", the twins argue who is responsible stating that "coughs and sneezles spread diseasels". The drivers stop the twins from arguing and make a plan to get the trucks back which involves removing the twins identifying plates and making them identical.

The twins find the trucks in a yard, with a large green Diesel at the front. Ben hides behind, with Bill going forward to demand the trucks back. The Diesel claims the trucks are his and tries to shoo Bill away, but when Bill disappears Ben rides forward surprising the Diesel (thinking it's the same engine). This continues for a while, causing the Diesel to get dizzy. The twins then reveal themselves to him.

Edward arrives at the scene and asks what Bill and Ben are doing there. They explain that the "dieseasel" stole their trucks, but Edward scolds them for their rudeness. The twins apologise and the Diesel forgives them. He introduces himself as BoCo and explains that he got his trucks mixed up with Bill and Ben's. Edward sends the twins to pick up BoCo's trucks.

After the two leave, Edward tells BoCo that Bill and Ben do not mean any harm but can be maddening at times. BoCo laughs and replies that "maddening is the word".

Characters

 * Edward
 * Bill and Ben
 * BoCo

Locations

 * Brendam
 * Wellsworth
 * Sodor China Clay Company

Trivia

 * This episode is based on the story of the same name from The Railway Series book, Main Line Engines.
 * As Bill and Ben puff into the shed near BoCo's train, to the left of the shed, there is a soup can in the foreground.
 * One barge has "Steve" written on it and a boat is labelled "Terrey". This could be a reference to crew members Stephen Asquith and Terence Permane.
 * In Germany, this episode is named "Dieselitis". In Italy, the episode is titled "Only a Misunderstanding". The Croatian name is "Diesel Disease".

Goofs

 * One of Bill and Ben's drivers says "We'll take away your names and numbers", but the twins were not given numbers in the television series.
 * In the scene after Bill and Ben leave Brendam Docks, the twins do not disappear. They just stop right at the top of the screen. The end of the set can also be seen in a still from the episode.
 * When Bill and Ben puff through Wellsworth, studio equipment is visible at the top.
 * Bill and Ben are said to puff into the shed behind BoCo when they actually are in the shed next to him.
 * The narrator says Ben (on BoCo's right) went forward, but he goes to the left in the next shot.
 * When Ben comes up next to BoCo, BoCo looks to his right, but when Bill comes up BoCo does not look to his left.
 * In the restored version, when Bill and Ben puff away from their trucks, two hands can be seen pulling them backwards with string. In addition, the tracks lead to a dead end.
 * In the American narration, the narator says "Bill pretended not to be frightened", which does not make sense as Bill still pretends to be frightened after BoCo tells him to go away.
 * When the narrator says "Bill took his place", the track where Ben was previously bounces up.
 * When Edward arrives, his bogie is derailed.
 * When the twins apologise to BoCo, Edward disappears, indicating that the footage from where Bill was accusing BoCo of being a bully was used at that point.
 * As the camera moves towards BoCo at the end of the episode, part of the studio is reflected in his windows.
 * When the twins come back to the china clay trucks, they should have been pulling more.