A year has gone by since Jim Button and his best friend, the engine driver Luke, returned from their dangerous adventure in Dragon City. Life on Morrowland goes its leisurely way again. Suddenly, dark clouds are gathering over the tranquil island of Morrowland: the notorious pirate gang "The Wild 13" has learned that the dragon Mrs Grindtooth has been conquered by Jim and Luke and now swears 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 they meet old friends like princess Li Si, Mr. Tur Tur and Nepomuk and make new friends with Sursulapichi, a real mermaid. On their adventure, Jim's most fervent wish might also come true: to find out the truth about his mysterious origins.