The Dubious Pranks of Shaindy Goodman

SHAINDY is a twelve-year-old Orthodox Jewish girl who struggles in school and has no good friends. She watches with envy as her next-door neighbor, GAYIL, excels socially and academically. They have little to do with each other, and it comes as a surprise when Shaindy looks out her window one September evening and sees Gayil staring out at her from her own window with a sign reading want to know a secret? 

The secret (at first) is that Gayil has a key fob that will allow them to break into their school after hours. Together, they set up a harmless prank in their classroom. But under Gayil's instigation the mischief becomes malice, and Shaindy sees that the pranks and humiliations are targeted only at certain girls. But what could they have in common? With the fear of Gayil's fury and her own reluctance growing,  Shaindy comes to the terrifying conclusion that if she can't figure out how to stop it, the next target could be her.