At fifteen years old, Abigail Costa might not know much, but there are three things she's absolutely certain of: Her grandmother, Nonna, is a superhero and she wants to be just like her one day. The world is round and she wants to see absolutely every inch of it. And she and Elliot Peterson will be best friends for life. After over a decade of getting up to no good together and spending every possible moment in one another's company, it seems impossible that anything could ever change. Enter: the new girl. With perfect blonde hair and a body to die for, she's everything Abbi never realised she wanted to be. And as she starts to notice that something isn't right with Nonna, she finds that some of her certainties aren't quite so certain anymore, and loneliness forces her to dig deep for a strength she never knew she had