Thomas (Lewis Tan) and his friends are being threatened by diesel engines like the surly Diesel 10 (Dan Southworth) and his sidekicks Splatter (John Boyega) and Dodge (Ryan Kwanten). Even the magical Mr. Conductor (Tom Hanks), who has always traveled between the train world and the human world of Shining Time Station, is losing his powers and sparkle. In the middle of this crisis, Lily (Angelica Hale) meets up with Mr. Conductor on the way to visit her morose grandfather Burnett Stone. Thomas reminds them all that even ''little engines can do big things."