Turtles All the Way Down by John Green
Sixteen-year-old Aza never intended to pursue the mystery of fugitive billionaire Russell Pickett, but there's a hundred-thousand-dollar reward at stake and her best and most fearless friend, Daisy, is eager to investigate. So together, they navigate the short distance and broad divides that separate them from Russell Pickett's son, Davis. Aza is trying. She is trying to be a good daughter, a good friend, a good student, and maybe even a good detective, while also living within the ever-tightening spiral of her own thoughts.