She is "Kimmie's little sister" and Kimmie is off to college. Her aunt tells her that an old friend is coming to spend the summer. He is given Kimmie's room and he finds Muffy's diary and we're shown what it contains via flashbacks.
United States of America
81 minutes
1985
Sharon Mitchell
Gourmet Video
1985
6.5
2005
7.1
2008
6.4
2006
7.3
2003
6.9
2009
5.8
1988
6.0
2008
3.8
1970
5.8
2014
7.1
2013
6.0
1964
5.0
2014
0.0
1966
7.4
1992
0.0
2018
4.2
2019
5.3
2001
7.6
2009
6.6
2007
3.9