The inheritance. Young Jeff MIller inherits Lassie from a farmer neighbor. In his frantic and often heart-breaking efforts to win the dog over, Jeff accidentlally uncovers a mystery and assists in the capture of a thieving farmhand.

Lassie's pups. At the height of a raging storm, Lassie decides to give birth to a litter of pups. She has a difficult time of it and needs help to save her life.

The transition. Timmy overhears Ellen tell Jeff that the Child Welfare Agency will not let her adopt him. Timmy runs away and Lassie follows.