Thomas & Friends: Sodor's Legend of the Lost Treasure

Thomas the Tank Engine is racing on his branch line with Bertie the bus. When Bertie gets stuck behind an excavator on the road, he complains about all of the machines working on a new branch line, which concerns Thomas' coaches Annie and Clarabel. Marion the railway steam shovel meets up with Oliver the Great Western engine and his brakevan Toad at Arlesdale junction, where she meets Mike, Bert, and Rex, the miniature engines, for the first time. They are delivering ballast for the new branch line.

The next morning, Thomas causes Gordon the Big Engine's express to fly off the tracks by accident while trying to disprove the latter about "silly" tank engines. Thomas tries to pin the blame on the other engines, but Sir Topham Hatt angrily tells Thomas that he was the one who caused the accident. As punishment for his actions and making up excuses, Sir Topham Hatt takes away Thomas's branch line and gives it to a new engine named Ryan. He then sends Thomas to the construction yard of the new branch line, much to Gordon's delight.

Meanwhile, at Arlesburgh Junction, Mike, Rex, and Bert burst into song to cheer Thomas up. At the construction yard, Thomas goes over an unsafe section of track as it gives way for a large gap. Thomas falls into the sinkhole and is badly damaged by the fall. He sees, however, an old abandoned pirate ship inside and, when lifted out by Rocky the crane, he tries to tell Sir Topham Hatt about it, but he ignores him, believing that Thomas is making up excuses. While Thomas is being repaired at the works, he learns that Rocky has found a ship at the bottom of the cavern. Thomas is furious when he learns that Rocky has taken the credit for his discovery due to Sir Topham Hatt's refusal to listen to him. Donald and Douglas, the Scottish twin engines, are tasked with taking the ship to the harbor to put it on display. As they do so, the same man from before watches them. That evening, Henry the Green Engine encounters a ghostly sailboat on the rails.

The next day, Ryan is transferred to the new branch line while Percy the Small Engine takes over for him on Thomas' branch line. That evening, Thomas suddenly wakes up and follows the same sailboat that Henry saw. Just outside the sinkhole, Thomas accidentally makes himself known, and sailor John and sailboat Skiff introduce themselves. Thomas soon agrees to help find the treasure and lowers Sailor John into the cavern, where the map is found. Late next morning, after taking on bad coal, sparks from Ryan's funnel light the dynamite in his trucks, which he and some other engines pass around before Thomas shunts the trucks into the cavern, right before it explodes. Thomas is congratulated by everyone for saving all their lives, but an enraged Sir Topham Hatt intervenes, thinking that Thomas was messing around with the dynamite. Thomas tries to explain what really happened, but Sir Topham Hatt, who is fed up with his actions, refuses to listen and confines him to his shed for the rest of the afternoon. The diggers try to carry on, but without the dynamite, they are unable to make progress. The construction vehicles leave for the evening while Marion finds a chest within the cliffside.

That night, Thomas agrees to help Sailor John to again find the treasure, but when their search for the treasure comes up empty, he soon gets accused of finding it first. An upset Thomas bumps into Marion, who drops the chest onto him, revealing the treasure. Marion is praised for finding the treasure by Sir Topham Hatt, while Ryan is sent to pick up more dynamite and Thomas is sent to take trucks of rubbish to the dump as punishment for yesterday's incident. Passing through Knapford, Thomas overhears Sir Topham Hatt on the telephone, saying the treasure will be in his office overnight. Back in the construction yard, Ryan apologizes to Thomas for getting him into trouble and offers him a place to sleep in the sheds, but Thomas declines and decides to sleep in Knapford station for the night, believing John will try to steal the treasure. That night, Thomas sleeps in wait just outside the station, while John blows up the safe and takes the treasure. The explosion awakes Thomas, who begins pursuing him. Chasing them to the top of a hill, he finds the pirate ship, which John has rigged as an escape vehicle and tied to Skiff. Mike, Rex, Bert, and Ryan assist Thomas in derailing the pirate ship as John and Skiff continue towards the harbor.

As the morning sun rises, Thomas is still chasing the pair, but Skiff encourages Thomas to derail him. Thomas accidentally sends him down a wrong line, but soon notices that his line crosses over Skiff's - which runs into the sea. Thomas slips into it and rests atop of Skiff's chassis, while John sails away, despite Skiff asking him to throw off the heavy treasure, which a huge wave sinks to the bottom of the sea. Later that morning, the police turn up and arrest John. Upon seeing Sir Topham Hatt, Thomas, worried that he is still angry at him due to him causing so much trouble these last few days, tries to own up to his mistake this time, but Sir Topham Hatt is happy for his heroism for saving the construction yard and for trying to stop Sailor John after Ryan explained everything to him. Although Thomas is upset that he was unable to save the treasure, Sir Topham Hatt kindly tells him that his engines are more important than any treasure.

At last, the construction is complete. To everyone’s surprise, Sir Topham Hatt informs all the engines present that the new branch line will be given to Ryan and Daisy the diesel railcar, who previously worked on Thomas' branch line. A fully repaired Thomas cuts the ribbon and leads the other engines down the new branch line, meeting up with Skiff again, who is now carrying out railboat tours to visitors, while some divers recover the treasure.

• Thomas & Friends: Sodor's Legend of the Lost Treasure at IMDb

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