Book of Lies
Piper and Quinn find out they're identical twins when their mother dies; Piper was the lucky one she kept, and Quinn grew up with her strict grandmother out in the middle of nowhere.
Piper has a flexible relationship with the truth and Quinn is forbidden to lie, which makes life interesting - not least for Piper's boyfriend, Zak. But is family ever as black and white as truth and lies, or one good and one bad twin?
Written with alternating viewpoint chapters between Piper and Quinn, the twins' perceptions and versions of reality interplay expertly as the story builds to its dramatic climax.
Both are believably flawed characters, and the family history develops to give a genuinely spooky feel to this excellent psychological and supernatural thriller.