Twins Parker and Charlie are polar opposites.

Where Charlie is fearless, Parker is careful.

Charlie is confident while Parker aims to please.

Charlie is outgoing and outspoken; Parker is introverted and reserved.

And of course, there’s the one other major difference: Charlie got leukemia. Parker didn’t.

But now that Charlie is officially in remission, life couldn’t be going better for Parker. She’s landed a prestigious summer internship at the hospital and is headed to Harvard in the fall to study pediatric oncology—which is why the anxiety she’s felt since her Harvard acceptance is so unsettling. And it doesn’t help that her relationship with Charlie has been on the rocks since his diagnosis.

Enter Finn, a boy who’s been leaving strange graffiti messages all over town. Parker can’t stop thinking about those messages, or about Finn, who makes her feel free for the first time: free to doubt, free to make mistakes, and free to confront the truth that Parker has been hiding from for a long time.

That she keeps trying to save Charlie, when the person who really needs saving is herself.