Margo has just about everything. She's pretty and pert, and everyone calls her Muffy. But for Margo, that's not quite enough. She wants to be known for somethingother than her looks and her sweetness. She wants to be #1, to hit it big in some different way. And the chance occurs when each person in her class is given the opportunity to learn to play a musical inistrument.

Margo soon finds out, however, that she has met her match with her clarinet. In fact, when Muffy brings it home to show to her family, she's greeted with a less than enthusiastic response. Her mother seems to wash clothes that are already clean just to escape Muffy's "music" and her sister and brother beg for silence.

Muffy comes up with a plan: she'll hire a professional listener. Misty, a sophomore in high school, is the perfect choice. She's a good musician, she's a good teacher, she's fair, and she's strict.

Misty sets up rules and an unbreakable schedule, and as a result Margo, Peter, Helena and Leroy form a group called teh Unrelated Siblings. Leroy, the math wiz, calculates that they need to improve by 110% to become the best in the school. And this will include triumphing over the stuck-up Ernestine, who's had private music lessons for over a year.

Determined to reach their goal, the kids practice individually. They practice together. They practise without an audience, they practice in front of crowds. They play in the wind, the rain, the cold, and the heat. They enter parades and contests—anything to keep playing music, to keep rehearsing for the bigtime.