In this installment, Mia Thermopolis frets over whether or not her boyfriend, Michael Moskowitz, will take her to prom. While she initially expects an invitation given that they're happily in love after the events of the previous novel, Mia learns during her birthday party that Michael isn't interested in going to prom at all.
At her birthday dinner that same night, a busboy named Jangbu spills a meal on Grandmère's suit at and she has him fired on the spot. This leads to a citywide busboy protest, with Mia's best friend Lilly aligning herself with the busboys. Much to her ex-boyfriend Boris's chagrin, Lilly also shows romantic interest in Jangbu. To prove his love for Lilly, Boris says he'll drop a globe on his head if she doesn't take him back. Lilly refuses him, and he accidentally does so, injuring himself. After Mia and Lilly's friend Tina Hakim-Baba comforts him, she begins dating Boris.
When the prom is canceled due to the busboy strike, Grandmère pulls strings to secure a new venue and gives Mia an idea to convince Michael of how to come to prom: to get his band to play there. In exchange for providing the premises, Mia successfully blackmails Lana Weinberger into letting Michael's band play at the prom. Helen goes into labour and delivers her and Mr Gianni's baby, a boy named Rocky; Jangbu accepts an exclusive deal with a newspaper and returns to his native country, leaving Lilly dismayed; and the strike ends with improved pay for the busboys.
