In a small Yorkshire village during the Great Depression, financial pressures cause the parents of young Joe Carraclough to sell his beloved dog, Lassie, to the Duke of Rudling. After the duke takes the collie to his Scottish estate, his granddaughter recognizes that the dog misses her former owner and allows her to escape. Facing great dangers and small kindnesses on her lengthy journey, the faithful dog sets forth to rejoin her beloved family.