Girl Falling by Scrivenor Hayley - SIGNED BY AUTHOR

"Why would my best friend want to destroy my life?

Finn and her best friend, Daphne, have grown up together in the Blue Mountains. Bonded by both having lost a younger sister to suicide, they've always had a close - sometimes too close - friendship. Now in their twenties, their lives have finally started to diverge: Daphne is at university and Finn is working in the Mountains, as well as falling in love with a beautiful newcomer called Magdu.

Unused to sharing Finn, Daphne starts to act up in ways that will allow her to maintain the control over her best friend she's always relished. 

Then, one fateful day, Finn, Daphne and Magdu all go rock-climbing - and Magdu falls to her death. Is it suicide, or a terrible accident - or something more sinister?"