Let's start with the blurb:
Having been diagnosed with cancer, Cass Goldman decides to opt out of any futile medical care and end her life. While she has some thoughts on afterlife, she never expects to reincarnate into the body of a seventeen-year-old girl named Casey Davidson.
When she awakens in a hospital, Cass discovers two disturbing facts: One, she is now inside the body of a troubled teenager, and two, the former owner of this body committed suicide, but only Cass knows that. Everyone else believes Casey has survived, but suffered a complete memory loss. Cass has two choices: to take on Casey’s life and turn it around, or to confess the truth about her reincarnation and end up in a mental asylum. Given this second chance at life, Cass decides to take on the future life of Casey—the frightening ghoul-faced teen with short, black, spiky hair.
Every person around Cass has an ulterior motive and discovering the truth of Old Casey’s life is more complicated than the “new math” she is forced to learn in school. In addition, Cass has to contend with raging teenage hormones and the prior crimes of Old Casey, which she might not remember, but everyone else certainly does. However, her biggest frustration concerns her feelings for her father’s rugged security specialist who sees her only as a teenager and doesn’t want to explore the mutual attraction between them.
As determined as Cass is to turn this life around, Old Casey’s enemies are just as determined to end her life. She has no idea whom she can trust, but she knows she’ll never survive going it alone.
And... here's an excerpt! =)