Middle-schooler Gideon Quinton wasn't thrilled about moving with his family across the U.S. to nowhere Nevada right at the start of summer break. When he arrives to his new neighborhood, he notices there's a girl next door about his age who wears a baby blanket as a cape, rainbow socks up to her knees, and a swimsuit over her shorts and tee to skate outside. He quickly learns this getup is Roona's alter ego's supersuit, for when she needs to be Wonder Roo, and she takes him on (un-Gideon-like) wild, hobbit-like adventures. After some troublemaking and truth-telling, he learns much more than he thinks he can handle about Roona's homelife and is stuck: Break his promise to not tell his parents what's happening or get her and her mom the help he knows they need? For the reader, especially any adult reader, this story is heartbreaking. For the young reader, it's not much easier, but Grimes offers a story that's easy to engage with, told through a kid narrator who cares and wants to do right by everyone.

Gideon's unhappy that his family moved to Nevada the summer before seventh grade. He is, however, intrigued by next-door neighbor Roona, even though she sometimes wears a blanket cape and talks about magic. But Roona's life is complicated, leaving quiet, sheltered Gideon quickly out of his depth. Themes of parental mental illness and abuse are handled sensitively in this surprisingly weighty friendship story.