Diesel's and Dragons was uploaded on June 21, 2017 and is the fourth episode of the fourth season.
A certain diesel that all engines fear is terrorizing poor Percy. However, Percy looks to a certain artifact from his past that might put Diesel 10 in his place.
- Diesel 10
- Arry and Bert
- Toby (does not speak)
- Duck (cameo)
- Alice and Mirabel (cameo)
- Harvey (cameo)
The Chinese Dragon is not considered a character as it is a prop.
- Sodor Scrapyards
- The Smelters
- The Viaduct
- Tidmouth Sheds
- Lower Suddery (flashback)
- Elsbridge Harbor
- Wellsworth Dairy
- This marks the first real appearance of Diesel 10 in The Engines of Sodor, not counting his cameos in earlier episodes.
- The title is a parody of the game "Dungeons and Dragons".
- The Chinese Dragon model was made by Crovan's Gate Works, shortly before they shut down. It was not re-uploaded when they returned in 2016.
- Events from the TV episode Thomas, Percy, and the Dragon are shown in a flashback.
- The original idea for this episode was to be a story involving Percy and James switching jobs.