Going in, I definitely thought this would be a fantasy book akin to The Hearts We Sold. It's definitely more of a supernatural mystery instead - tracking down those marked by the devil, as uncertainty grows about the nature of this organization. Matt is on his first solo assignment, but he quickly begins to lose objectivity when he meets Rachel. To be fair - who would assign a cute teenager as a "project" to a young boy? There are some chilling twists thrown in, but overall it's a pretty straightforward supernatural thriller.

*Thank you to Razorbill and NetGalley for an ARC in exchange for my honest review*