The story is like this: There is a girl who is in love with a guy who's older than her, and she really wanted to sleep with the guy so she dressed up to be older than her actual age which I think is 15 or something like that. But on her way home, she is gang raped and horrible deformed because she was beaten and raped so many times.
She had to go through plastic surgery to keep her face and body, got a new name and began to work as an undercover agent of sorts. Then her boss brings in a newcomer who just happens to be the guy she loved in her childhood. She gets all cranky at her boss for making him her partner, but they work together for a case in which they act as husband and wife pretending to get an adopted child through the assistance from an illegal organization.
They work together, there is attraction, and the girl falls in love again. The guy realizes who the girl is from the colour of her eyes, and demands that he knows the truth from the boss. The boss hands him a file in which he comes to find out what happened to the girl.
The unfortunate fact is that I didn't have a chance to finish the book. T^T And that is why I'm looking for it.
There are two scenes in the book that I remember.
One is when the guy meets the girl (all dressed up), when they were both younger, and while dancing, he gets erect. And he continues to dance close to the girl until the girl widens her eyes from the realization that he wants her.
Two is when the guy is gripping the file, leaving his drink aside, horrified by what happened right after the girl left his place to return home.
It was a really good book so if anyone knows this book or read a book similar to it, please by all means reply. I'd like to know if it's the one I'm looking for.

Call the reader's advisory desk/reference desk at your library. They have databases and print resources to help identify romances and other books. Or check the Romance Writers of American web site and post this question there.