Guardian of the Gate — Michelle Zink

The ultimate battle between sisters is nearing, and its outcome could have catastrophic consequences. As sixteen year-old Lia Milthorpe searches for a way to end the prophecy, her twin sister Alice hones the skills she'll need to defeat Lia. Alice will stop at nothing to reclaim her sister's role in the prophecy, and that's not the only thing she wants: There's also Lia's boyfriend James.

Lia and Alice always knew the Prophecy would turn those closest to them against them. But they didn't know what betrayal could lead them to do. In the end, only one sister will be left standing.