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“Why does Luke have to hide away like that? Why is he so scared of being found? What could he have done that could be bad enough to be sent away from Sodor?”

Blue Mountain Mystery is a Thomas & Friends special released on DVD and Blu-ray in September 2012. It is the seventh Thomas film in the franchise.


It is a busy day at the Blue Mountain Quarry and as Paxton is pulling away from Owen with his loaded trucks, the keystone from Blondin Bridge falls down from above. Rheneas is travelling towards the crumbling bridge with his heavy slate trucks which push him onto the bridge. Rheneas just manages to clear the bridge before it gives way. Rheneas thunders down the line at high speed, knocking into walls on his way. When he comes to a stop, he is badly scratched, but not hurt. Paxton, on the other hand, isn't been so lucky and has been derailed by rubble from the bridge. He is in need of urgent repair.

On Thomas' Branch Line, Thomas is working with Annie and Clarabel when a small red car lurches around the bend carrying the Fat Controller. Thomas is surprised, but the Fat Controller explains that it is Winston, his new track inspection vehicle. The Fat Controller tells Thomas that Paxton has been involved in an accident and that he is to take Paxton's place working at the Blue Mountain Quarry.

Thomas hurries to the quarry and spends the day working hard with his narrow gauge friends. When evening arrives, Thomas takes his trucks to Brendam Docks and returns to Tidmouth Sheds for the night. The next morning, Thomas is shunting trucks in the quarry when a mysterious green engine darts from a tunnel. Thomas introduces himself, but the little green engine does not reply and quickly rattles into another tunnel. Thomas asks Sir Handel who the green engine is, but Sir Handel tells Thomas he must have mistaken it for a runaway truck and hurries away. Then Thomas sees the green engine pulling slate trucks. He asks Rheneas who he is, but Rheneas says that he does not know. Later on, Thomas sees the little green engine emerge from behind a shed. Thomas calls out to him, but the engine races away. Thomas decides to ask Rusty about the green engine, but the little diesel hastily tells Thomas that it must have been a mountain goat and rolls quickly away. Thomas makes his way to Skarloey, in hope that he will be able to tell him about the green engine. Just then, the little engine reappears and screeches to a halt. The little engine freezes and stares at Thomas before racing toward a tunnel.

Just then, Rheneas puffs out of the tunnel, accidentally blocking the little engine's path. Rheneas yells out an apology, "I'm sorry, Luke!" and Thomas overhears him. He continues to follow the little engine, but the engine gets blocked by Sir Handel and Peter Sam as well. Rheneas then clears a path for him, leaving the little engine racing back into the tunnel. Thomas then confronts Skarloey and asks him who Luke is, why he keeps puffing away and why none of the others will talk about him. Skarloey decides that since Thomas is a friend, he can be let in on the secret. Skarloey tells Thomas that long ago Luke did something very bad and that he thinks if anyone finds him, he will be sent away from Sodor forever.

That night, Thomas asks his friends at Tidmouth Sheds what the worst thing an engine could do is. The engines think hard and Percy remembers the time when he tried to sneak up on the coaches, but ran into a baggage trolley and covered himself and the Fat Controller in jam. Henry thinks of the time that he did not want his paint to be spoiled and stayed in the tunnel, only to be bricked up inside. Thomas recalls the time he ignored a "Danger" sign and fell down a mine. James mentions the time Diesel pushed the Jobi wood trucks into the sea, though they all agree that none of that was bad enough to be sent away from Sodor.

The next morning, Blue Mountain Quarry is very busy. Rocky is moving stones from Blondin Bridge. Thomas arrives and finds Rheneas complaining to Skarloey about needing a new coat of paint after his accident. Thomas tells Skarloey that he has asked his friends and they have all decided that nothing is bad enough for an engine to be sent away forever. Skarloey turns stern and asks Thomas if he has told his friends about Luke. Thomas says that he has not told them and that he wants to help Luke and be his friend. Skarloey is satisfied and reverses down the line. He does not see Rocky lifting rocks across his track. Thomas shouts out a warning and Skarloey manages to stop just in time. Skarloey thanks Thomas who is pleased that Skarloey is able to trust him.

As Thomas works, Luke puffs out of hiding and pulls up alongside Thomas. Luke apologises for hiding and tells him that he was scared. Luke then asks Thomas if they can be friends. Thomas is very pleased and the two engines work together contently. Suddenly, the sound of a horn echoes around the quarry. This startles Luke who quickly goes into hiding. Winston whizzes around the bend carrying both the Fat Controller and Mr. Percival and pulls up beside Thomas. The two controllers thank Thomas for his hard work and tell him that Paxton is now fixed and will be resuming his usual duties at the quarry. With that, Winston rattles away. Thomas rolls over to Luke's tunnel and says goodbye. Thomas asks Luke about what he did to fear being sent away from Sodor. The little engine promises to tell Thomas if he tells no one else. Thomas agrees to keep the secret and Luke tells Thomas that it all happened when he first arrived on Sodor. On the boat he arrived on, there was a yellow engine who spoke a different language that Luke could not understand. When they arrived at the docks, the men wanted to lift the yellow engine off first, but an excited Luke asked to be lifted off first. The dock workers agreed. As Luke pauses ominously, Thomas asks him to continue. Luke then tells Thomas that he knocked the yellow engine into the sea. Luke then recalls having to go to the Steamworks, but all he could think about was the yellow engine. The yellow engine was left in the sea for a long time and when he was finally lifted out, he was rusty and ruined. The yellow engine was never seen again and Luke assumes he must have been sent to the Smelter's Yard as he was not fit to work. Suddenly, Thomas hears Skarloey shouting at Paxton who bolts out from behind some trucks. Thomas questions what Paxton is doing and the diesel stutters that he has come to take over from Thomas and Paxton speeds away. Thomas looks back towards Luke, but the little engine has vanished. Thomas calls a final goodbye into the tunnel and leaves.

The next morning, Thomas asks Toby to work on his branch line while he sets out to find the yellow engine. At the Sodor Dieselworks, Thomas spots loads of engine parts, but none of them yellow. As Thomas rolls out onto the forecourt, he hears something that makes his boiler run cold; Paxton is telling Diesel all about Luke and what he had done all those years ago. Diesel is adamant that he does not want an engine that is capable of knocking another engine into the sea on the island. He tells Paxton that they will tell the Fat Controller who will tell the Thin Controller and together they will send Luke away forever. Thomas does not want to hear another word and steams away as fast as he can. Diesel sees Thomas and tells Paxton that they must find out what trickery Thomas is doing.

As Thomas races down the line, he attempts to ask Cranky about the yellow engine and suddenly gains an idea; the rusty engine would have been taken to the Sodor Steamworks. When Thomas puffs in, he asks Victor if he recalls fixing a yellow engine that had fallen into the sea and spoke a different language. Victor stops dead in his tracks and makes an exclamation in Spanish. Thomas realises that Victor was the yellow engine that had fallen into the sea. Victor then tells Thomas what had happened; While he was on the boat, a big wave broke the weak chains holding him to the ship's deck. Victor remembers calling to the dock workers, but they could not understand his language. As Luke was being lifted, he swayed on the end of the hook and knocked into Victor into the sea. Because of the bad weather, Victor was left in the water for a long time and when he was taken out, he was in a terrible state. As no one could understand him, Victor decided to learn English and since he was in need of a repaint, his first word was "red" as that was the colour he wanted to be.

Thomas races away from the Steamworks, determined to reach the Blue Mountain Quarry before Paxton and Diesel. While heading to the quarry he sees Diesel with Paxton telling the Fat Controller what Paxton told him. But the Fat Controller does not know what he is talking about and orders Diesel to push Mavis to the Dieselworks for repair and for Paxton to work at the quarry. As they leave, Thomas races to the quarry. As he arrives, Luke puffs out from the quarry hills to greet Thomas who calls out that he has spoken to Victor about the incident, but gets interrupted, then is unable to say more when Skarloey asks what he did. Skarloey interrupts him and tells Thomas that he had made a promise not to mention Luke to the other engines. All the engines are cross, including Luke. They all tell Thomas that he's no longer their friend. Diesel's horn echoes around the quarry, he pulls up behind Thomas with Paxton close behind. Diesel looks up and spies Luke at the top of a hill. Thomas tells the little engines not to listen to Diesel, and asks them to let him explain, but now knows that his narrow gauge friends will not let him explain his side of the story and feel that Thomas has let them and Luke down.

Thomas puffs to the foot of the hill and begs Rocky to lift him onto Owen's platform so that he can reach Luke and explain to him. Owen starts to pull Thomas slowly up the hill. Diesel shouts up to Luke, telling him that Thomas cannot help him now and that he will have to leave the island. Luke believes Diesel and raced away as Thomas rises towards him. Diesel tells Paxton to bring the Fat Controller, but Thomas tells him to go to the Steamworks to get Victor. As Thomas reaches the top of the incline, he shoots off the platform to chase after Luke, but Thomas has forgotten that the lines in the hills are for narrow gauge wheels only. Thomas tries to back onto the platform, but his wheels cannot grip. Instead, Thomas rolls forwards and is soon hanging dangerously over the cliff's edge.

The little engines see that Thomas is in trouble, and they all immediately forget to be cross, instead being worried about him. Luke buffers up behind Thomas and declares that he must help save his friend. Thomas laughs in relief, but finds that he is not out of danger yet. As Thomas rolls onto Owen's platform again, Luke slips onto the platform too. The platform groans under the weight of the two engines and gives way. The two engines hurtle toward the quarry floor at a tremendous rate. Owen tugs at the winch in order to slow down the platform. It finally bounces to a stop at a lower level of the quarry. All of the engines cheer and whistle, pleased that no one was hurt.

Suddenly, Winston arrives carrying Mr. Percival and the Fat Controller. The latter is furious to find Thomas causing confusion and delay at the quarry, instead of working his branch line. The Thin Controller orders Rocky to lift Thomas and Luke down. Diesel oils forwards to explain to the Fat Controller about Luke. Thomas does not have time to reply before Paxton enters the quarry, pushing Victor on a flatbed. Victor has come to meet an engine he has not seen in a very long time. He tells Luke that he did not push him off the boat, he slipped off and it was an accident. Luke does not believe that Victor is the same engine as the one that plummeted into the sea until Victor speaks in his native language. The Fat Controller realises that Diesel was wrong, and tells him it is always important to find out the entire story, because what really happened is what really matters. Mr. Percival welcomes Luke to his railway, and the Fat Controller tells Thomas he is proud of him, and will forgive him for not working on his branch line. Luke is happy for the first time in a long time, and he tells both controllers that Thomas is his hero and his friend.

A few days later, Thomas goes to the Steamworks. Luke is there with Victor who jokes that he has found a yellow engine. Rheneas then puffs out of the Steamworks smiling. He has been given a new coat of bright yellow paint. Thomas beams from buffer-to-buffer; a bright new colour really does mean a new life for his friends, and he and everyone else laughs.


Characters Introduced



US and CAN


  • Ben Small as Thomas, Toby, Rheneas and Owen
  • Keith Wickham as Edward, Henry, James, Percy, Skarloey, Sir Handel, the Fat Controller and Mr. Percival
  • Teresa Gallagher as Emily, Mavis, Annie and Clarabel
  • Matt Wilkinson as Rusty, Winston, Rocky, Cranky, Kevin, Merrick, the Blue Mountain Quarry Workman and the Dock Workers
  • Steven Kynman as Paxton and Peter Sam
  • Michael Legge as Luke
  • David Bedella as Victor and the Cuban Dock Workers
  • Kerry Shale as Diesel

Bonus Features

UK and AUS


  • "Blue Mountain Hide & Peep Game"
  • "Learn About Standard and Narrow Gauge Engines" video
  • Blue Mountain Mystery music video
  • Working Together music video


  • Blue Mountain Mystery Theatrical Trailer
  • King of the Railway Trailer
  • Sir Takaboushi Hideki's Introduction


  • This special went into production at Nitrogen Studios in August 2010.[1] It has a copyright of 2012; Nitrogen Studios wrapped up production on the show for the final time in March that year.
  • This special takes place between the fifteenth and sixteenth series.
    • However, this special was released after the sixteenth series, presumably based on production order.
  • This was the first time in the CGI series that scenes from model-era episodes were recreated as flashbacks. This would become commonplace for the remainder of the series' run.
  • This special was shown in select US, UK, German and Australian theatres.
  • This is the last special of several things:
    • The last special written by Sharon Miller.
    • The last special animated by Nitrogen Studios prior to Arc Productions taking over in 2013.
    • The last special narrated by Michael Angelis in the UK prior to his passing in May 2020, and the last special narrated by Michael Brandon in the US and Povl Dissing in Denmark.
    • The last special in which Jules de Jongh voiced Mavis and Michael Brandon voiced Diesel in the US.
    • The last special where the narrator has more dialogue than the characters.
    • The last special to appear on Cartoonito UK.
    • The last special produced by HiT Entertainment under ownership of Apax Partners, as they sold HiT to Mattel on the 1st February 2012 after the special was produced.
    • Whiff's last appearance in a special until Journey Beyond Sodor, five years later.
    • Sir Handel's last appearance in a special until The Great Race.
    • Mavis' last speaking role in a film.
  • This is also the first special of several things:
    • The first special narrated by Michiel de Jong in the Netherlands and Philippe Catoire in France and French-speaking Canada.
    • The first special where David Bedella voices Victor in the UK dub taking over from Matt Wilkinson.
    • The first time a second language is featured in the English dubs: Victor speaking Spanish.
    • The first special where the character's have slightly more dialogue like the narrator does.
    • The first time the Skarloey Railway engines interact with standard gauge engines other than Thomas and James since the fifth series.
    • The first special to have a prologue before the main titles. This would be the case with every subsequent special until Digs and Discoveries.
    • The first special since The Great Discovery to have songs during the runtime, rather than at the end. Also, the first special to feature more than one song since that said special.
    • Rheneas and Peter Sam's first speaking roles in a special.
    • The first special in which Hiro does not appear since his debut in Hero of the Rails.
    • This episode marks the first two things for Rusty:
    • James' first speaking role in a special since Hero of the Rails in the Japanese dub.
    • The first special where Paxton is voiced by Steven Kynman, as he took over the role from Keith Wickham. Thus, Steven Kynman joins the voice cast.
    • Paxton's full introduction, as he was only a background character in Day of the Diesels and the fifteenth series.
    • The first appearance of the Skarloey Railway and its engines, Mr. Percival's first speaking role and the first time he is referred to by name since the twelfth series episode, Push Me, Pull You. It also marks the Skarloey Railway engines' first appearances in CGI.
    • The first appearance of Old Bailey in CGI and his first appearance since the fifth series episode, Haunted Henry.
    • The first special to have a mid-credits scene.
    • The first special not to get a Polish DVD release, the second being Big World! Big Adventures!.
    • This special marks the first of a few things for Annie and Clarabel:
  • This is also the only special of a few things:
    • The only special in which Gordon appears, but does not speak.
    • The only special in which Owen speaks, as well as the only one in which he is voiced by Ben Small.
    • The only special where Merrick speaks.
    • The only time in CGI to use the Märklin Engine.
    • The only appearance of Luke in the Nitrogen Studios era.
    • Owen, Merrick, Annie and Clarabel's only speaking roles in the Nitrogen Studios era.
    • The only time the narrow gauge engines appeared in a Nitrogen Studios special.
    • The only special to have Park Jeong-uk and Shin Song-i as part of the voice cast for Green Narae Media in South Korea.
    • The only special in the CGI series to feature the entire UK voice cast in the US dub.
  • Michael Legge joins the voice cast.
  • Andrew Brenner, who took over as head writer from the seventeenth series to the twenty third, worked as a script editor on this special.
  • Recreated CGI flashbacks and references from the first series episode, The Sad Story of Henry and Down the Mine and the third series episode, A Scarf for Percy and a flashback or edited stock footage from Misty Island Rescue are used.
  • A scrap model of the Märklin Engine can be seen as Thomas enters the Dieselworks.
  • The working title for the special was The Runaway Engine.
  • This special aired on PBS on Thanksgiving 2012, on Milkshake! on New Year's Day 2013, on Nick Jr. on December 2013 and later on Easter Sunday 2013 and on ABC 2 on Easter Monday 2013. It also aired on Cartoonito UK on 25th October 2018.
  • Nitrogen Studios released "The Blondin Bridge collapse and Rheneas' runaway" sequence to the public in their Studio Animation Pipeline collection illustrating the three various stages of animation the film went through before the final cut. In the first stage (storyboard sketch) the last two trucks fall from Rheneas' train during the collapse of Blondin Bridge. This results in a more serious derailment for Paxton. The falling trucks were removed before the next production stage. Also, the keystone that lands beside Paxton in the final render lands directly onto the tracks in front of him in the first storyboard/stage.
  • This special was released in the same year that Minaz No. 1173, Victor's basis, was rescued from Céspedes Sugar Mill.
  • The US release is missing some fade effects.
  • Thomas going down Owen's incline was inspired by a real life event with a Manning Wardle L Class (Billy and Charlie's class) locomotive during 1925.
  • The "Learn About Standard and Narrow Gauge Engines" segment on the DVD/Blu-ray release marks the first mention of the Culdee Fell Railway in the television series.
  • The US release was slowed down and adds an extra two minutes to the special's length. As a result, the audio is distorted. However, the US iTunes release is not affected by this.
  • In the Latin American, Brazilian Portuguese and French dubs, Victor's first language is Greek.
  • The Official Charts Company revealed that this special was voted popular pre-school DVD of 2012 in the UK.
  • The events of this special are mentioned by Luke in the seventeenth series episode, Luke's New Friend and by Ben and Timothy in Big World! Big Adventures! during the song, Where in the World is Thomas?
  • Duncan was going to be included, but when the production crew went to the Talyllyn Railway to measure the engines, his basis was being overhauled, and could not be measured. Because of this, he was left out until the eighteenth series.
    • Had Duncan been included, this would have been:
  • This is the fourth special not dubbed in Hebrew.
  • This special's Korean title was just a transcription to Hangul of the original one.
  • This is the second special not released on DVD in South Korea.
  • In Green Narae Media's Korean dub, the singers for Working Together and the Blue Mountain Mystery song were credited in the theaters release, but strangely, they were not VOD release.


  • When the workman tried to stop Rheneas, he was holding a green flag instead of a red flag.
  • The narrator's description was a bit out of sync with what was happening when Rheneas went onto the bridge. The narrator said that Rheneas needed to cross the bridge before it collapsed when Rheneas was already off the bridge and the bridge was starting to collapse.
  • In the Brazilian dub, the narrator said that Paxton was telling about Luke to Diesel 10, however he was talking to Diesel.
  • Henry is in his new shape during the flashback to the first series episode, The Sad Story of Henry. This mistake would also be carried over when the story was retold again in The Adventure Begins.
  • Thomas stated that he steamed past the board and into a siding during his flashback to Down the Mine. However, he actually went into the siding first.
  • The ship carrying Victor and Luke had a chain around the edge, but the chain is missing when Luke is being unloaded.
  • Paxton is not coupled up to the trucks when he pulls away after eavesdropping on Luke's story.
  • The track that Thomas is on when he hears Diesel talking to the Fat Controller lead to buffers.
  • When the narrow gauge engines go onto the upper terrace to get away from Thomas, Rheneas' paint is no longer scratched.
  • When Rusty leaves Thomas at the crossover track, Rusty is making puffing sounds like a steam engine.



  • Hideaway Luke (discontinued)
  • Paxton in Trouble (discontinued)
  • Rheneas' New Coat of Paint (discontinued)
  • Blue Mountain Quarry Blast (discontinued)
  • Peter Sam's Blue Mountain Supplies (discontinued)
  • Talking Victor's Big Splash (discontinued)
  • Risky Rails Bridge Drop set (discontinued)
  • Blue Mountain Gravel Delivery set (discontinued)

Motor Road and Rail

  • Luke
  • Winston
  • Mystery of the Blue Mountain Yellow Victor and Kevin

Wooden Railway

  • Luke (discontinued)
  • Winston (discontinued)
  • Victor Comes to Sodor (discontinued)
  • Sea Soaked Victor (discontinued)
  • Yellow Rheneas (discontinued)
  • Blue Mountain Quarry Gift Pack (discontinued)
  • Skarloey and the Gravel Cars (discontinued)
  • Blue Mountain Mine (discontinued)
  • Deluxe Mountain Quarry (discontinued)
  • Boulder Pass (discontinued)
  • Grinding Gravel (discontinued)


  • Luke (discontinued)
  • Winston (discontinued)
  • Victor Comes to Sodor (discontinued)
  • Victor's Great Splash (discontinued)
  • Rheneas' New Coat of Paint (discontinued)
  • Sir Handel's Day at the Quarry (discontinued)
  • Tales From the Past Engine Pack (discontinued)
  • Paxton at the Blue Mountain Stone Shed (discontinued)
  • Slate Loading Station (discontinued)
  • Great Quarry Climb Playset (discontinued)

Capsule Plarail

  • Luke
  • Yellow Victor
  • Winston
  • Owen
  • Blondin Bridge

Mega Bloks

  • Blue Mountain Crew (discontinued)
  • Blue Mountain Quarry (discontinued)


  • Luke
  • Blue Mountain Crossing Set


  • Yellow Victor
  • Sea Soaked Victor


  • Yellow Rheneas (coming soon)

Collectible Railway

  • Winston
  • Luke
  • Charlie's Day at the Quarry


Magazine Stories


  • Handcraft Underwear (discontinued)

In Other Languages

Language Title
Czech Záhada Modré Hory
Danish Mysteriet på Blårjerget
Dutch Het Mysterie van de Blauwe Bergen
Finnish Sinivuoren Salaisuus
German Das Geheimnis um den Blauen Berg
Hungarian A kék hegy rejtélye
Indonesian Misteri Gunung Biru
Japanese ブルーマウンテンの謎
Korean 블루 마운틴 미스터리
Latin American Spanish El Misterio de la Montaña Azul
Norwegian Blåfjellsmysteriet
Polish Tajemnica Niebieskiej Góry
Portuguese A montanha azul misteriosa
Romanian Misterul de pe Muntele Albastru
Serbian Misterija Plave planine
Slovenian Skrivnost Modre Gore
Swedish Mysteriet pa Bla Berget
Taiwanese Mandarin 蓝山矿场的秘密

DVD Packs