Zen and Xander Undone — Amy Kathleen Ryan

ZEN AND XANDER VOGEL ARE SISTERS-TRULY, MADLY, DEEPLY SISTERS-AND THIS IS THEIR LAST SUMMER TOGETHER.

Zen is hopelessly virginal, with a black belt in karate and a newfound penchant for kicking heads. Xander is a wild scientific genius with a self-destructive streak a light-year long. They have three things in common: they're brown-eyed blondes, they've noticed the boy next door has turned into a hottie, and they miss their mom, who died almost a year ago.

The Vogel sisters are surviving just fine, except Zen keeps getting into fights that are harder and harder to finish, and Xander is spiraling into a vortex of late-night parties, scary men, and dangerous drugs. What's worse, Xander has scholarships to the most coveted universities in the country, but she's about to ruin everything. Should Zen keep trying to protect Xander, or finally let her go?

In the midst of the chaos, a bird figurine mentioned in their mother's will leads them to discover a strange man from their mother's past, a man she'd kept hidden. The mystery deepens with each letter they receive from their dead mother. Who is John Phillips and where are these letters coming from?

As Zen and Xander pursue the mystery of their mother's past, they may find that this cache of secrets will be the bond that holds the crumbling Vogel sisters together.