Jaclyn Hyde is almost perfect. Whether she’s baking cookies for her classmates, building a replica Mount Vesuvius for the science fair, or practicing her lines for Fog Island: The Musical, she almost never makes mistakes. But when she discovers the last batch of perfection potion in an abandoned laboratory, Jaclyn decides that being almost perfect isn’t perfect enough anymore.

But it turns out being perfect isn’t all it’s cracked up to be—in fact, it’s downright horrifying. Instead of making Jaclyn the best version of herself, the potion turns Jaclyn into Jackie, a goblin-like monster who’ll do anything to make sure Jaclyn comes out on top. Suddenly, she’s wreaking havoc on the school play, stealing bake-sale brownies and passing them off as her own, and even destroying someone’s painting so she’ll win “Artist of the Week.” And that’s just the beginning. Jackie will stop at nothing to make sure everyone knows just how perfect Jaclyn really is. So now, if Jacklyn wants to save her school, her friends, and herself from her perfectly horrifying alter-ego, she’s going to have to screw up her courage and risk it all—even if that means admitting that she never was as perfect as she seemed.