In a small Yorkshire village during the Great Depression, financial pressures cause the parents of young Joe Carraclough (Roddy McDowall) to sell his beloved dog, Lassie, to the Duke of Rudling (Nigel Bruce). After the duke takes the collie to his Scottish estate, his granddaughter (Elizabeth Taylor) 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.