The Dirt on Ninth Grave by Darynda Jones

Charley Davidson is living in New York City as Jane Doe, a girl with no memory of who she is or where she came from. So when she begins to realize she can see dead people, she's more than a bit taken aback. Strangers who enter the diner where she works seem to know things about her...Then she is confronted by a man who claims to have been sent to kill her. Sent by the darkest force in the universe. An enemy that will not stop until she is dead. Thankfully, she has a Rottweiler. And the diner's devastatingly handsome fry cook, who vows to protect her even though he seems to be lying with every breath he takes. But in the face of such grave danger, who can Jane/Charley/whoever she is trust? She will find the truth even if it kills her...or the fry cook. Either way.