I read this book the day after I read Vintage, and the two actually make surprisingly good companion novels. Both feature realistic teens with serious problems, both main characters can see and talk to ghosts, and both books are excellent.
Sixteen-year-old Cass hates everyone in her school except Norris and Bitzy. They happen to be ghosts, and her only friends. Four years before, Cass's former best friend, Danielle, turned on her and made sure everyone else in the school did too. Cass has discovered a foolproof way to keep from being bullied: have her ghost friends spy on students and report everyone's nasty little secrets to her. As a result, Cass's school life is lonely but bearable.
Also four years ago, Cass's older sister Paige died--and didn't leave. Paige gives Cass the big-sister advice and encouragement she never gave when she was alive.
When Tim, one of the most popular kids in school, asks Cass to help him contact his recently-deceased mother, she only agrees because she plans to make him give her dirt on Danielle. But Tim turns out to be a genuinely nice guy who is overwhelmed with a grief that no one he knows can understand.
Cass's defensiveness and anger feel very real. She's tough and resourceful, but she doesn't recognize Tim's attempts to make friends with her. In her experience, people only act friendly when they want something. Tim's problems are realistic too, as is his increasing desperation to find relief from his pain. I cried for the last hundred pages of the book, but it was a good cry.
If the book has a fault, it's that Cass and Tim tend to be a little too articulate about their feelings than most teens are capable of. It works with the story, though. I loved watching Cass learn how to deal with living people again, a slow and sometimes painful process. I also loved the details about the ghosts: that they can't remember things very well, that each ghost has a particular scent (and even taste) that Cass can pick up on.
The ghosts aren't scary in this book, but the living people often are.
Note: The cover is horrible. Disregard it.