Sixteen-year-old Aza Holmes would rather not go looking for a missing billionaire, but her fearless best friend Daisy smells a hundred-thousand-dollar reward, so the two set off toward the fugitive's estranged son, Davis. What begins as an amateur investigation keeps circling back to the thing Aza cannot escape: the tightening spiral of her own intrusive thoughts. John Green, author of The Fault in Our Stars, writes her interior life with unusual clarity, balancing a mystery, a tentative romance, and a portrait of anxiety that never softens into easy comfort. It is a story about trying, and about the friendships that hold when a mind will not.