Mischa Kenning-Elliott is seventeen, super bright and, until recently, about as dramatic as her 8 am Econ lectures. She’s a happy mid-bottom dweller on the Centerville High social food chain and is focused on things like college applications and avoiding the dreaded f word—another flare of her lupus.

Ever since he was adopted in the seventh grade, Casey Everfeld’s life has been going according to plan, too. He’s Centerville’s star pitcher, popular, and predictable in his own way right up until he asks Mischa to prom.

Now, Mischa’s seeing the same number everywhere and knowing things she shouldn’t. Now, she and Casey are a thing. A serious thing. A thing she doesn’t want to give up.

There’s just one problem: someone’s trying to kill her.