On their way to start a new life at a sheep farm in rural Virginia, the Turner family are halted by a wreck on the highway that has claimed the life of a truck driver. Spotting the trucker's now-abandoned collie on the side of the road, they take pity on the dog and adopt her. As the city family copes with the change to rural life, including a feud with a neighboring farm family who resent the city interlopers, the ever-loyal Lassie helps them adjust to their new surroundings.