Marcia is distraught after getting braces and becomes convinced she's ugly. This compounds when her boyfriend Alan breaks their upcoming date, thinking it's due to her braces. Meanwhile, the Brady kids try their best to make Marcia not feel so self-conscious but with little success.

When Cindy accidentally puts Marcia's diary in the collection of books to be donated to a local book drive, Marcia is crushed when she finds out what happens and vows to never speak to Cindy again. The family then sets out to find her diary before a stranger can read her deepest, darkest secret is that her crush is Desi Arnaz, Jr.