Main Page

This article is about the episode. You may be looking for the book or the DVD.
“Oh dear! I never meant to upset her. What if I've upset her so much that she's run away?”

Runaway Engine is the fifth episode of the twenty-first series.


Millie is given extra work around the estate, so the Earl tells Glynn and Stephen of the jobs they have to do, despite their constant chatter. Millie gets agitated when Stephen forgets to clear up garden waste, so she dumps it in front of his shed in the estate. Rather than an apology, Stephen makes fun of her, hurting her feelings.

By the next day, he tries to apologise to her, but cannot find her, leading him to think that she must have run away. Going out of his way away from the estate to look for Millie, Stephen runs out of water while pulling his passengers.

To Stephen's luck, Millie, with the Earl on board, find him. Millie and the Earl explain that she had gone for a new motor for the estate castle's turntable and that he and Glynn were not listening to his orders yesterday morning. The Earl sorts out the stranded passenger train - soothing an angry passenger - and Millie, Stephen and Glynn make up again.






  • Going by production order, this is the tenth episode of the twenty-first series.
  • A few references to the seventeenth series episode, The Switch are made, such as when Skarloey asks Millie if she was at the Blue Mountain Quarry to help the narrow gauge engines for the second time.
  • This is the first episode of a few things:
  • This episode marks the only occurrence of a couple things:
    • The only appearance in the twenty-first series of all the vehicles who appear in this episode.
    • The only episode in the twenty-first series in which Thomas does not appear at all.
  • This episode marks the last occurrence of a few things:
    • The last episode (and the fourth overall) to have the same cast in both English dubs, after the seventeenth series episodes, Luke's New Friend and The Switch and the twentieth series episode, Blown Away.
    • The last episode that does not physically feature Thomas until the twenty-third series episode, Heart of Gold, and the final episode to not feature Thomas in any way, as he takes over as narrator from the twenty-second series onwards.
    • Rheneas' last appearance in an episode to date.
    • Stephen and Luke's last speaking roles to date.
  • This episode's title was also one of the working titles for Blue Mountain Mystery.
  • During the close-up of Mr. Bubbles, he is holding a blue, yellow and red balloon, which represent Millie, Stephen and Glynn respectively. The blue balloon then flies away, symbolising that Millie had gone missing.
  • A picture of Glynn from The Adventure Begins, a promo picture of Stephen and a picture of Ulfstead Castle from King of the Railway can be seen on the brochure that the Grumpy Passenger is holding.
  • In the Nick Jr. USA airing of this episode, it was paired with the twenty-first series episode, Confused Coaches.
  • A shortened version of this episode, narrated by Joseph May as Thomas, can be found on the official YouTube channel and the Nick Jr. website.


  • When Stephen and Glynn discover the garden waste, Stephen's shed doors are shut. But when Millie puffs on the turntable, the doors are open.
  • In the overhead shot of Millie backing up to the loading shed at the Blue Mountain Quarry, a narrow gauge train is travelling on standard gauge rails.


In Other Languages

Language Title
Brazilian Portuguese A Locomotiva Fugitiva
Japanese ミリーをさがせ!
Korean 스티븐의 오해
Polish Obrażona Lokomotywa
Romanian Locomotivă Scăpată de Sub Control
Spanish Locomotora Fugitiva

Home Media Releases


External Links


*Disclosure: Some of the links above are affiliate links, meaning, at no additional cost to you, Fandom will earn a commission if you click through and make a purchase. Community content is available under CC-BY-SA unless otherwise noted.

Fandom may earn an affiliate commission on sales made from links on this page.

Stream the best stories.

Fandom may earn an affiliate commission on sales made from links on this page.

Get Disney+