Dark clouds are gathering over the tranquil island of Morrowland, the home of twelve-year-old Jim and his best friend, Luke the Engine Driver. The notorious pirate gang "The Wild 13" has learned that the dragon Mrs. Grindtooth has been conquered by Jim and Luke and now the pirates swear revenge! To protect Morrowland from another threat, the two of them set off with their steam engines, Emma and Molly, on a dangerous journey where Jim's most fervent wish might also come true: he wants at last to find out the truth about his mysterious origins.