Turtles All the Way Down

Turtles All the Way Down
By John Green

From the author of A Fault in Our Stars, another heartbreaking story; this one about a teen with a mental health illness. But this book is both a romance and a mystery!
This review is from Publishers Weekly Annex:

Like many of Green's characters, Aza Holmes is whip smart, articulate, and tortured by worry. When she was eight, her father succumbed to a heart attack while mowing the lawn. Now 16, Aza takes meds (irregularly) to treat anxiety, which is manifesting in increasingly self-destructive ways. Her problems amplify when she reconnects with Davis, a boy she met years earlier at "Sad Camp," where both had gone to grieve their recently deceased parents. Now Davis's billionaire father is missing, running from a warrant for his arrest. Aza's best friend Daisy, in a classic sidekick role, pressures Aza to contact Davis, hoping they'll learn something about the disappearance-and maybe get a cut of the $100,000 reward. The reunion leads to romance, until Aza's anxiety won't allow it...