The Antiques Roadshow is coming to Clark and everybody brings something they think might be valuable for the Englishman to check out. After a lot of junk, Ellen discovers that the Monopoly her sister Mary gave her years ago that had never been opened is worth thousands of dollars - enough for Ellen to move out, since Ellen feels she's intruding Catherine and Dot's space.

Mr. Munn is going out of town for a principal's conference and leaves Ellen in charge. She decides she'll rule the school differently, with lighter rules, no detention and more field trips. Of course, her plan backfires when all the detention kids take over Catherine's pharmacy, someone cleans up the principal's room, Pam spends the entire French club budget redesigning the teacher's lounge in 17th Century France style, Rusty is almost electrocuted while taking the kids to a field trip and much more. Ellen decides then to have a 8:30pm basketball to help the kids release their anger, but the gym is locked. She goes to Mr. Munn's place to get the key and finds him sitting watching television. Turns out he just wanted a little time off and thought Ellen was doing a better work than he.

Ellen decides to surprise Dot by flying in her aunt Mary, to whom Dot hasn't spoken in years. Mary buys everyone very expensive gifts, going against Dot's rule of hand made, inexpensive presents. They also fight about Mary's successful career and Dot's way of life. Feeling resented, Mary decides to go back to Chicago, and it's up to Ellen to save the Richmonds Christmas now. She has a word with Dot, who finally decides to accept her sister and leave behind all the hard feelings between them. Unfortunately, there's nothing left to eat, except for Pam's gingerbread house.