From Darkness : A Novel

"Sixteen-year-old Ari Wyndham lost her best friend in the sea. Everybody told her it was an accident, but Ari can't forgive herself. Her own life is cut short when a tiger-snake delivers a deathly bite, and a beautiful, ghostly and strangely familiar young woman appears, summoning Ari's soul to the underworld. Ari, however, refuses to go. Though she knows there will be a terrible price to pay for her transgression, the mysterious guide chooses to save Ari. Their rebellion upsets the balance of life and death in Ari's remote coastal village. A rift opens from the underworld, unleashing dark magic: savage dog packs emerge at night, fishermen catch ghostly bodies in their nets, and children go missing"--