Albert finds himself unsure of his identity when Miss Wilder assigns the students a family tree project. The trouble is, just as the Ingalls are getting ready to adopt him officially, Albert's long-estranged biological father shows up and demands custody of him.

A circus act passes through Walnut Grove, and Nels Oleson is horrified when he spots his estranged sister Annabelle as "the fat lady." Embarrassed by her physical appearance, Nels denies any relation to her.