Jock Gray raises his collie Lassie to be an extraordinary sheep dog and companion. When he is beaten to death by robbers after he retires, Lassie keeps vigil over his grave and refuses to let anyone else take ownership...展开of her. However, the law requires that all dogs be leashed and licensed by a legal owner. With no owner to pay her license and her only "home" being the church graveyard, Lassie faces an uncertain future.
Her late owner's friend John Traill, his law student son, and the keepers of the graveyard struggle to keep Lassie hidden from the zealous police Sergeant Davie and the town magistrate. Matters are brought to a head when they must go to court to plead for the dog's life before the Lord Provost.