Per her 537 rules, Harper Campbell keeps her life tidy-academically and socially. But the moment Sterling Lane transfers into her tiny boarding school, her twin brother gets swept up in Sterling's pranks and schemes and nearly gets expelled. Harper knows it's Sterling's fault, and to protect her brother, she vows to take him down. As she exposes his endless school violations, he keeps striking back, framing her for his own infractions. Worst of all, he's charmed the administration into thinking he's harmless, and only Harper sees him for the troublemaker he absolutely is.

As she breaks rule after precious rule in her battle of wits against Sterling and tension between them hits a boiling point, she's horrified to discover that perhaps the two of them aren't so different. And maybe she doesn't entirely hate him after all. Teaming up with Sterling to save her brother might be the only way to keep from breaking the most important rule-protecting Cole.