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“It's running loose!”

Rusty and the Boulder is the twenty-fifth episode of the fifth series. It aired back to back with Stepney Gets Lost on Storytime with Thomas in the US.


High up in the mountains, there is a giant, mysterious boulder that has stood alone for a long time. But one day, a new quarry is built near the mines on the land below and Rusty is afraid the boulder will fall onto the line. He confesses his fears to Thomas and Percy. Percy thinks it's nothing, but Rusty is convinced there's something mysterious about the boulder. Edward arrives with a new machine called Thumper to help with the mining process. Thumper soon starts working which the men are pleased with, but no one bothers to check the boulder. However, it starts raining and the workmen leave. Rusty gazes up and shivers at the boulder above. Suddenly, a large slab of rock lands on the tracks. Rusty is shocked and worried by this, but his driver is concerned that the rock has been loosened by the rain. Rusty however believes the boulder is telling them to go away and as they leave, a face mysteriously appears on it and then disappears.

The next day, Thumper begins working harder than ever. Suddenly, Rusty sees Boulder starting to move, but his driver does not believe him until Boulder falls down and lands in front of them with a thud and begins rolling along the tracks as Rusty quickly drives himself backwards to get away from it. Rusty and his driver stop at a junction and wait for Boulder to pass by, but it's nowhere to be seen. Then, they soon realise that Boulder is suddenly behind them and continues to pursuit them. Just ahead, they see a small junction with a line that goes uphill, so Rusty takes it while the Boulder thunders past them.

Meanwhile, Skarloey is on his way to the quarry shunting trucks, but he sees Boulder heading for him and immediately reverses. He soon slips into a siding, while the Boulder passes by, destroying the water tower in between the tracks. Skarloey tells Rusty that they have to warn the yards, but Rusty does not know how seeing how the line is blocked now. Boulder rounds a bend and charges towards Rheneas, who races back across the viaduct as fast as he can to get away from Boulder until he crashes into a siding with the Boulder just passing by him, much to the relief of his driver. At the yards, Percy is collecting trucks when he hears and sees Boulder approaching. Thinking Boulder is about to crush him, he shuts his eyes and his driver and fireman jump out. It rolls past, narrowly missing Percy and destroys the neighbouring sheds, engulfing them in flames and sparks (fireworks-like), finally coming to a stop.

When the Fat Controller inspects the destruction, he decides to close the mine. Then, looking at Boulder amidst the destruction it had caused, he lamentably concludes that they should have left this part of the island alone. Boulder is later moved to a small hill close by the yards so it will never harm anyone or anything on the island anymore. Rusty is sure that, on a clear night, it is gazing high up at the mountains in the distance and that its sighs are being carried on to the wind where it once used to stand, proud and silent.




  • Going by production order, this is the twenty-sixth episode of the fifth series and the series finale of the fifth series.
  • Boulder's face is based on Gordon's sad face.
  • The same model for Boulder is used for both the large-scale and normal-scale sets.
  • This is the only episode of three things:
    • The only appearances of Thumper and Boulder.
    • The only episode where Terence appears without his driver.
    • The only episode of the fifth series where Rheneas speaks in both English dubs.
  • This marks Rheneas' first speaking role in the US dub since the fourth series episode, Gallant Old Engine.
  • In this episode, the quarry was brand new and closed in a short amount of time, which implies the events of the fifth series episodes, Bye George! and Duncan Gets Spooked may have taken place during the events of this episode, as they also took place at the Boulder Quarry yards at the base of the mountain. Furthermore, George is seen at Thumper's dig site before Boulder gets loose, meaning that he served his week-long punishment and was brought back to the quarry to help.
  • The scenes where Boulder chases after Rusty, Skarloey and Rheneas are references to the boulder chasing scene in the Indiana Jones film, Raiders of the Lost Ark. This reference was later used again in the Thomas' YouTube World Tour short, Thomas Goes for Gold, and the twenty-third series episode, Mines of Mystery.
  • Rusty's small-scale model is used at the beginning and end of the episode, whilst his large-scale model is used for the remainder of this episode.
  • Rheneas' small-scale model is used when he is crossing the viaduct, whilst his large-scale model is used for when he starts escaping from the Boulder and crashes. In addition with the small-scale model, Rheneas' unused fourth series terrified face is used which was the first and only episode to feature the face mask.
  • A small connector is attached to Rheneas when the camera gets close-ups of him, while the boulder chases after him.
  • This is one of Davey Moore's favourite episodes alongside the first series episode, Thomas' Train and the seventeenth series episode, Luke's New Friend.
  • This is one of the three episodes to feature Thomas' unused third series jolly face, the other two being Something in the Air and Snow.
  • In the US and international dubs:
    • Music can be heard when Edward introduces Rusty to Thumper, and during the runaway when the Boulder is behind Rusty and Skarloey telling Rusty that they should warn the yards.
    • The sound of Boulder thudding on the ground is much different than in the UK dub of this episode. Also a second thud was heard only in the US dub.
    • The sound of Skarloey braking when he sees the Boulder is different.
    • The sound of the Boulder destroying the water tower beside Skarloey is less audible than the UK dub of this episode.
    • The crash sound is heard when Rheneas crashes into a siding with Boulder just passing by him.
  • In the UK dub, James' line "EYYOIIIKES!!!" was re-used from the fifth series episode, Busy Going Backwards for Skarloey and Rheneas, when Boulder charges after them.
  • Butch gains a face in this episode, as in his other appearances besides Horrid Lorry, he faced away from the camera.
  • This episode is the last time that Percy's original wincing face was used on-screen.
  • Despite not being seen or featured in this episode, Oliver is in the Wooden Railway set based on this episode.
  • After the boulder crashes into the sheds, a fireworks shot and explosion sound effect is heard.
  • This is the second and last episode of the fifth series where a building catches fire (after Thomas, Percy and Old Slow Coach).


  • Due to his model being changed, Rusty's face constantly changes size throughout the episode.
  • In the close-ups of Rheneas running backwards from Boulder, a camera rod can be seen attracted to his coupling hook.
  • In the close-up of Rheneas' driver after the crash, his right (viewer's left) pupil appears to be sloppily painted. Also, he appears to be in Rusty's cab instead of Rheneas.
  • In the US dub, when Percy is at the quarry before Boulder arrives, the British term "trucks" is used.
  • In the second close-up of Percy when Boulder is approaching, it appears that the shed has already been destroyed as the wood from the shed is laying on Percy's trucks. Also, the loads in Percy’s trucks change.
  • When Rusty says "It's rolling along our line!" Terence and some pipes can be seen behind him, but they disappear in the shots following.
  • Terence is missing a patch of his orange paint when Thumper starts working at the quarry.


  • Percy: Where's all this rock coming from?
  • Rusty: The new quarry. This mountain rock is good for many things, although it's dangerous up there.
  • Thomas: Why?
  • Rusty: Because of a big boulder. I think it's watching me.
  • Percy: How can it be? Boulders don't have eyes!
  • Rusty: UK dub: That's as may be, Percy, but there's something strange about this one. / US dub: Well, Percy, there's something strange about this one.
[Edward arrives with a machine named Thumper for the quarry]
  • Rusty: What's that?
  • Edward: It's called Thumper. Apparently, it helps collect the rock faster.


  • Rusty: [to his driver] I think it's the boulder wanting us to go away.


(Skarloey makes his way up to the quarry with some trucks/cars, but encounters Boulder)
  • Skarloey: (reverses to safety) UK dub: EYYOIIIKES!!! / US dub: HELP!
(Boulder catches up fast, destroying a water tower in the process but Skarloey safely reaches a siding)
  • Skarloey: We must warn the yards!
  • Rusty: Yes, but how?


  • Rheneas: It's running loose! UK dub: EYYOIIIKES!!! / US dub: Hurry!
[Rheneas races in reverse as the Boulder chases him, and then manages to safely race into a siding, but crash backwards]
  • Rheneas' Driver: (relieved) Better/Rather a smash than a squash!


In Other Languages

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Language Title
Albanian Rasti dhe Shkembi
Brazilian Portuguese Perigo
Chinese Mandarin 罗斯缇和石头
Czech Rusty a bludný balvan
Danish Rusty og Rullestenen
Dutch Rusty en het Rotsblok
German Rusty und der Felsblock
Greek Σκουριασμένο και το ογκόλιθος
Hungarian Rusty és a Vándorkő
Italian Rusty e il Masso
Japanese いわのボルダー
Korean 러스티와 둥근 바위
Latin American Spanish Rusty y la Roca
Norwegian Rusty og Rullesteinen
Polish Rusty i Głaz (Original)
Rudik i Głaz (Alternate)
Romanian Rusty și Bolovanul
Russian Расти и валун
Serbian Rasti i Veliki Kamen
Slovenian Zlatko in Skala
Swedish Rusty och Stenbumlingen
Welsh Y Graig

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