Turtles All the Way Down

Aza and her friend Daisy decide to try to solve the mystery of the disappearance of billionaire Russell Pickett in order to obtain the $100,000 reward. In the process, Aza reconnects with Pickett's son, Davis, who she met as a child after both she and Davis lost parents. Aza is under the care of a psychiatrist for spiraling thoughts, and the relationship she develops with Davis as well as the relationship she has with her long time friend, Daisy, are precarious.

This is my third John Green book, so I can say with confidence that it is a strong John Green novel.