From darkness : a novel
(Book)

Sixteen-year-old Ari Wyndham lost her best friend in the sea. When her own life is cut short, a familiar young woman appears and summons Ari's soul to the underworld. Ari refuses to go and the mysterious guide decides to save her. A rift opens from the underworld, unleashing dark magic. Together, Ari and her guide battle the dark powers of the underworld and heal the rift -- but it is up to Ari to do the one thing that will save the world from darkness.

Ari Wyndham has a secret. Her best friend, Alex, drowned at Stonehaven beach when she was nine, and nobody knows that Ari still blames herself. When Ari is bitten by a tiger snake, Alex-- now a summoner-- is sent from the underworld to collect her. They recognize each other, and Alex chooses to save Ari, even though she knows there will be a terrible price to pay for this transgression. The balance of life and death is upset, and endangers the people and animals of Stonehaven. A rift opens from the underworld, and dark magic threatens the remote coastal town. And there is only one thing that will save the world from darkness. -- adapted from Amazon info