Lassie is set on the eve of World War II in a Yorkshire mining town. After falling on hard times, the Carraclough family is forced to sell Lassie, their beloved dog, to the Duke of Rudling. When she succeeds in escaping her cage, Lassie finds herself transported five hundred miles away to the Duke's remote castle on the northern coast of Scotland. However, she is determined to defy the odds and return to the home she loves. So begins an incredible adventure, set against a stunning series of landscapes, that sees Lassie facing dangers both natural and human and finding help in unexpected places as she makes her way across the country, to reach home in time for Christmas.