The Thirteenth Circle by Connolly

Cat knows aliens are real, and she’s determined to prove it. By studying her town’s legendary crop-circle phenomenon for the McMurray Youth Science Competition, she’ll not only demonstrate the existence of extraterrestrial life but also impress her distant NASA-scientist father.

Dani does not believe in aliens. So when Dani is paired with Cat for the competition—which she has to win to avoid her parents’ artsy summer camp—she knows she’s in trouble. Her solution? Disprove Cat’s theory, of course . . . without letting her partner know.

But as the girls bond over science, it becomes clear that there is something strange about the crop circles. And when Dani and Cat’s project is threatened by mysterious forces, they’ll have to work together to expose the truth once and for all.