Hero of the Rails.One summer on the Island of Sodor, Spencer (voiced by UK: Matt Wilkinson/US: Glenn Wrage) arrives to help the Duke (voiced by UK: Matt Wilkinson/US: William Hope) and Duchess (voiced by UK: Teresa Gallagher/US: Jules de Jongh) with the construction of their new summer house. After being an absolute nuisance to all of the other engines by teasing and bossing them around, Thomas (voiced by UK: Ben Small/US: Martin Sherman) accepts Spencer's challenge to a contest of strength, taking heavy cargo around the island. Thomas's brakes fail after climbing a tall hill, and he runs out of control through an overgrown, abandoned line. There, Thomas finds an old abandoned Japanese engine named Hiro (voiced by Togo Igawa). Hiro doesn't want the Fat Controller (voiced by UK: Keith Wickham/US: Kerry Shale) to find out, fearing he will be scrapped, so Thomas promises to keep him his secret and work to make Hiro "Master of the Railway" once again. Later, he's taken to the Sodor Steamworks for repairs, where he finds old parts for Hiro. He takes them with permission from Victor (voiced by UK: Matt Wilkinson/US: David Bedella), the Steamworks engine, only to discover that Hiro's hiding place is dangerously close to the Duke and Duchess's new summer house. The following day, Thomas tells Percy (voiced by UK: Keith Wickham/US: Martin Sherman) about Hiro, and asks him to do his own job while he helps Hiro. Percy misplaces his own mail trucks and breaks down while doing Thomas's job, so Thomas brings him to the Steamworks. The Fat Controller finds out about this and scolds Thomas by forcing him to do Percy's work. With nobody else to ask for help, Thomas tells the rest of his friends about Hiro. They all work together in bringing Hiro new parts, distracting Spencer, and keeping the operation a secret from the Fat Controller while Thomas and Percy try to find the missing mail trucks. Hiro makes friends with all of the engines, but gradually grows homesick. On the day that the last necessary part for Hiro is to be delivered, Spencer discovers Percy's mail trucks, only to be cornered by Thomas, James (voiced by UK: Keith Wickham/US: Kerry Shale) and Toby (voiced by UK: Ben Small/US: William Hope). The Fat Controller accuses Spencer of stealing the trucks and demands he return them to Percy...