Vesper by Jeff Sampson

Emily Webb has always felt left out. The other Emily at school is popular and pretty. Until one night she's found murdered. No one knows who did it, just that there's a killer on the loose. Emily Webb goes through changes at night. She can't explain it, doesn't know what it's from. But as her "nighttime" Emily, she has confidence, speed, and power. Something that the daytime Emily does not. As she goes through her changes, she realizes the killer is targeting her kind.

This was a really odd book. Can't say that I loved it but I made it through. It didn't flow very well so I had a hard time reading it and getting through it. Didn't find out until the middle of the book that Emily actually is changing into a werewolf, which was a surprise to me. During this story, Emily is battling with having a somehwhat split personality. Her regular self is not what she would like it to be, she's invisible. Her nighttime self is anything but. Then add to the mix a killer who's trying to eradicate her kind because they are experiements gone wrong.