A circus comes to Walnut Grove. Everybody is helping set up, except Nels Oleson. His long, lost sister is in the circus. Only Mrs. Oleson believes her husband's story about his sister. Nels is nominated to be the announcer at the circus. When he announces his sister, he says, ""My sister, Annabelle."" These words lead to Nels and Annabella becoming very close siblings.
Cast: Michael Landon, Karen Grassle, Melissa Gilbert, Melissa Sue Anderson, Rachel Lindsay Greenbush, Sidney Greenbush, Richard Bull, Alison Arngrim, Scottie MacGregor, Jonathan Gilbert, Merlin Olsen, Hersha Parady, Patrick Labyorteaux, Matthew Labyorteaux, Linwood Boomer