The Purgatorium (Purgatorium #1‪)‬

Seventeen year-old Daphne Janus is surprised when her parents let her go with her friend to a getaway resort on an island off the coast of California. They haven't let her out of their sight since last New Year's Eve, when she could no longer stand the way they looked at her.

Her sister would still be alive if it weren't for Daphne.

Her friend, Cam, takes her to a mostly uninhabited island with a wildlife preserve on one side and Chumash Indian ruins on the “haunted” side. Daphne decides she will have one last "hurrah" before she finishes what she started last New Year's Eve. However, things seldom go as planned...

The resort is beautiful, the beach pristine, and the views from the headland amazing. The only thing missing is the boyfriend who left her when she could no longer love anyone. Then strange things begin to happen on the island that soon have Daphne running for her life. She eventually learns that her parents have sent her for experimental "suicide therapy," but when her horse bucks her off during a trail ride and she becomes lost on the haunted side of the island, she wonders if her parents have sent her there to help her or to punish her.