In a world where monsters exist, they can steal time off the end of the life of humans.  Also, the hero is the bad guy.

Joan finally learns (and has her world turned upside down) she is half monster/half human when she accidentally touches a man's neck and travels through time. Now the boy she likes slaughters her whole family and her world is turned upside down yet again.

I don't know why Joan's family didn't let her know their secrets sooner, she might have been spared a lot of heartache. I enjoyed the fact that a boy who comes from a family who hates her family helps her in this journey of trying to fix things.