Journey Beyond Sodor is a 2017 straight-to-DVD film.
Determined to prove his importance on Sodor, Thomas takes James' trucks and sets off on a big adventure to the Mainland. On the way he makes friends with the cheerful and helpful "Experimental Engines," but, after a wrong turn, finds himself lost in the steelworks. There, Thomas encounters two mysterious engines who instantly make him feel welcome, but who are not what they first seem...
After Thomas fails to return, James sets off to the Mainland, but runs into trouble himself and so it is up to Thomas and the Experimental Engines to save the day.