Thomas & Friends: Sodor's Legend of the Lost Treasure is a 2015 British animated fantasy adventure film and the ninth feature-length special in the Thomas & Friends television series.^[3] The film is produced by HIT Entertainment with animation production by Arc Productions. The film centres on Thomas unwillingly getting caught in a conspiracy to steal recently-discovered pirate treasure.

The film stars John Hasler (UK) and Joseph May (US) as the voice of Thomas, alongside special guest stars Sir John Hurt as Sailor John, the film's main antagonist and Eddie Redmayne as the purple tank engine Ryan. It also stars Jamie Campbell Bower as Skiff the sailboat, who would later reprise his role in the series. The film also marks the screen debut of Rex, Mike and Bert, who appeared in the twenty-second book of The Railway Series, "Small Railway Engines", and are based on locomotives from the Ravenglass and Eskdale Railway. Several other characters who had made long absences in the TV series, such as Donald, Douglas, Daisy and select members of the Sodor Construction Company, make their return in the film.

The film received a limited theatrical release in the United Kingdom in July 2015.^[1] It was met with mostly positive reviews from critics, who praised the direction and plot but were critical of the film's somewhat dark undertone.

Thomas the Tank Engine wins a race against Bertie the Bus, who mentions that a new branch line is being built. This concerns Annie and Clarabel, who fear that Thomas' branch line may be closed down. The next morning, Thomas plays a prank on Gordon the Big Engine for teasing him, which causes a major derailment. As punishment for his actions, Sir Topham Hatt sends Thomas to assist in constructing the new branch line while the new tank engine Ryan is granted Thomas' job in the meantime.

At the construction site, part of the terrain subsides underneath the new track. Thomas does not notice the danger signs and falls into a cavern where he finds a pirate ship. He tries to inform Sir Topham Hatt about the ship, but Hatt refuses to listen, believing Thomas is only making excuses. Rocky the crane is instead credited with discovering the ship, which is displayed at Arlesburgh Harbour. That night, a partially-repaired Thomas meets Sailor John and his boat Skiff, who has been fitted with wheels that allow him to travel on rails. John says he is looking for treasure but is hesitant to give Thomas details.

The next day, Thomas still cannot return to his branch line and has to continue working at the construction site, now alongside Ryan. Ryan accidentally ignites his trucks full of dynamite after taking on bad coal. Thomas saves Ryan and gets rid of the dynamite, but Hatt is furious, believing that Thomas was chasing Ryan with the dynamite. Thomas is unable to explain the truth and Hatt confines him to his shed for the rest of the afternoon. Marion the steam shovel finds a treasure chest full of gold and jewelry, which Hatt keeps in his safe overnight intending to donate it to the museum. Thomas meets a furious John, who reveals that it is the treasure he had been looking for and demands it to be handed over. Thomas says that Hatt has the treasure and refuses to help John take it.

That night, John breaks into Hatt's office and steals the treasure, using Skiff and the pirate ship as his getaway. Thomas chases them through a junction where the minimum-gauge engines slow the ship by derailing their ballast trucks. A loose rope is caught on Ryan, who derails the flatbed carrying the ship, leaving John with only Skiff and the treasure.

At Arlesburgh Harbour, Thomas attempts to knock Skiff off of the rails to no avail. At the launch ramp, John rows Skiff out towards the sea, and Thomas ends up partially submerged and fully immobilised. Skiff knocks Sailor John and the treasure off of him; the treasure sinks to the bottom of the harbour, and Sailor John is soon arrested by the police. Thomas is rescued and attempts to apologize to Hatt, fearing he will still be cross with him. Instead, Hatt is proud of Thomas, as Ryan explained everything to him, and assures Thomas that he will always be his "number 1 engine".

When the branch line is completed, Sir Topham Hatt gives a fully-repaired Thomas his branch line back and lets him cut the ribbon to the new line. Free from Sailor John, Skiff begins giving tours around Arlesburgh Harbour, and the treasure is recovered from the ocean.

• John Hasler as Thomas
• Keith Wickham as Edward, Henry, Gordon, James and Percy
• Rob Rackstraw as Toby
• Teresa Gallagher as Emily
• Matt Wilkinson as Cranky and Kevin
• Steven Kynman as Jack

• Joseph May as Thomas
• William Hope as Edward and Toby
• Kerry Shale as Henry, Gordon and Kevin
• Rob Rackstraw as James
• Christopher Ragland as Percy
• Jules de Jongh as Emily
• Glenn Wrage as Cranky
• David Menkin as Jack

• Keith Wickham as Salty, Bert, The Fat Controller/Sir Topham Hatt, Bertie and additional roles
• Eddie Redmayne as Ryan^[4]
• Jamie Campbell Bower as Skiff
• John Hurt as Sailor John
• Steven Kynman as Duck
• Joe Mills as Donald, Douglas, Oliver, and Toad
• Olivia Colman as Marion
• Tim Whitnall as Mike and Oliver the Excavator
• Teresa Gallagher as Daisy, Annie, Clarabel and some children
• Tom Stourton as Rex
• Jonathan Broadbent as Bill and Ben
• Nathan Clarke as Alfie
• David Bedella as Victor

The film grossed £889,927 in the UK, US$72,928 in Hong Kong and US$2,510,062 in China for a total of $3,472,917 worldwide.^[2]

Sodor's Legend of the Lost Treasure currently holds an 80% "fresh" approval rating on Rotten Tomatoes, based on 5 reviews.^[5]

Andrew Pulver of The Guardian gave the film a 3/5 stating, "Like Tale of the Brave, Lost Treasure jams locomotive action together with a pop motif supposedly beloved of kids: Brave had dinosaurs, Treasure has pirates."^[6]

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