Fifth-grade best friends Katie-Rose, Milla, Yasaman, and Violet are determined to save a new student from Modessa's evil influence, but Katie-Rose is busy not flirting with Preston and all four are distracted by trying to organize Yasamin's sister's birthday party.

Throughout their senior year in high school, Zoe, Maddie, and Angela continue to share "instant messages" with one another about their day-to-day experiences as they consider college, sex, the importance of prom, and the inevitable end of their inseparable trio.

Fifth-graders Katie-Rose, Violet, Milla, and Yasaman seem to have little in common except their flower-related names, but they nurture their new friendship through a social-networking site and a campaign to have healthier snacks served at school.