Season 4 began airing on April 22, 2017 and, if everything goes to schedule this time, finish in December.
- The Great Railway Heist: A truck full of gold is stolen, and everyone is determined to find the burglars.
- Jim's Tale: Jim tells the engines his story.
- Steaming Sausage: Rheneas gets back at Sir Handel and Peter Sam for teasing him about his leaking steam problem.
- Diesels and Dragons: Diesel 10 is up to his old bullying antics, but Percy might have a way to get him to make a fool out of himself.
- Airhead: Harold starts to get a little boastful and cocky.
- Painful Memories: Henry has a traumatizing near miss with explosive fuel wagons and he now fears for his safety.
- Episode 31
It is possible that there will be eleven episodes instead of ten. One of them will be Christmas themed. Edward will have the main role in the last two episodes.
- Donald and Douglas
- Sir Topham Hatt
- Arry and Bert
- Diesel 10
- Sir Handel
- Peter Sam
- Ivo Hugh
The following are confirmed
The following are likely to appear
- By the end of the season, all original 11 NWR engines will have had at least one main role in The Engines of Sodor.