As they take an elk survey, Scott and Lassie's helicopter ride turns deadly when the vehicle has has mechnical problems and crashes in the snowy wilderness. Bert tries to at least fix the communications system, but that too is beyond hope; they must rely on their survival gear and wait for rescue.

Lassie, on her own now (no explanation is given), meets a young man traveling the countryside and his male collie, Duke. They later find haven, and the young man a job, at a ranch where the owner's young son has not spoken for years.

While Duke and his master move on, Lassie remains at the ranch, but her new puppies are endangered by the owner, who thinks the pups were sired by a killer dog.