On his way to deliver a goods train to Bridlington on the mainland, Henry suffers a crash at Vicarstown station from a faulty signal and has to be taken to the Steamworks for repair. Meanwhile, Thomas is fed up with James’ constant boasting and is upset that Sir Topham Hatt chose him to take Henry’s goods train to the mainland. Thomas decides to arrive at Vicarstown before James so he can take the train to Bridlington himself (“Somebody Has to be the Favourite”). However, Thomas gets lost at a busy junction with the Troublesome Trucks distracting him and arrives at a canal where Beresford, a crane, blocks his path. He refuses to let Thomas pass unless he tells him more about himself, but Thomas tricks Beresford and passes through (“Who’s Thomas?”).
Thomas arrives at a rundown shunting yard where he meets Lexi and Theo, failed experimental engines who are no longer in service. They provide him with more coal and water but are unable to help him find his way to Bridlington.
Thomas sets off once again and later finds himself at a massive Steelworks factory run by Hurricane and Frankie who friendly invite him to stay (“The Hottest Place in Town”). Thomas initially declines as he has to deliver the goods train, but the Steelworks engines persuade him to stay the night as it is already very late. The next morning, Thomas learns that Hurricane delivered his train to Bridlington in the night and Frankie convinces him to help out at the Steelworks as to return the favour. However, they refuse to let Thomas leave and Frankie is enraged when Thomas tries to escape (“I Want to Go Home”). Thomas attempts another escape during the night and is this time successful.
He meets Merlin, a third experimental engine who falsely believes he has invisibility powers, who helps him evade Hurricane and Frankie. Thomas is saddened that he was not able to do anything right and the experimental engines remark that he is just like them (“We Can’t Do Anything”).
Meanwhile, on Sodor, James is begrudgingly running Thomas’ branch line in his absence. Percy suggests that James go to the mainland himself to find Thomas. At Bridlington Goods Yard, James didn’t get any information about Thomas from the Mainland Diesels, but learns from the Troublesome Trucks that they were ultimately delivered by Hurricane who, coincidentally, is also there.
On his way back to Sodor, Thomas passes by Beresford who is still upset about being tricked earlier. Thomas sees that Hurricane and Frankie are taking James to the Steelworks. Thomas enlists the help of the experimental engines to rescue James. Theo and Lexi distract the Ironworks engines while Thomas and Merlin try to help James escape. The plan quickly goes downhill and Thomas is put in harm’s way when he almost gets melted by molten slag. Hurricane pushes him out of the way, but his wheels melt as a result. Frankie is upset that Hurricane will not be able to help her make deliveries and explains that they are overworked at the Ironworks, which is the reason they tried to enslave Thomas and James. Thomas suggests that the experimental engines help them out. Although they are unsure if they are capable, they are still happy to try.
On their way back to Sodor, Thomas and James apologise to each other. Thomas explains that being friends is more important than being the favourite (“The Most Important Thing is Being Friends”).