You've been warned - James Patterson

Nanny and amateur photographer, Kristin, is plagued by a horrifying recurring nightmare. In the nightmare she arrives at the aftermath of a shootout where she spies four bodies and a detective, and she can't help but photograph the ghastly scene. The following morning she is greeted with this very same scene as she walks to work.
Kristin's life is complicated: her lover Michael is a married man, and the father of the children she looks after. His wife is a nasty, icy woman. But things are set to get worse. She starts seeing and photographing the ghosts of dead people on the streets of New York. Yet in her photographs the bodies appear to be transparent, just like the bodies in her nightmare. Kristin feels like she's going mad, nothing seems to make sense...