Just when you thought the venerable "wolf in sheep's clothing" genre was exhausted -- Fatal Attraction, The Hand That Rocks the Cradle, Single White Female -- along comes The Perfect Nanny. The title alone tips viewers off that the nanny isn't perfect, and with a tiny amount of imagination one also knows exactly what each of the plot points(represented by dead bodies) is going to be. That the movie is as entertaining as it is owes a debt to the superlatively creepy performance of Tracy Nelson as the psychotic serial-killing woman who is just a little bit too obsessed with romance novels. Now we've gone and spoiled the mystery -- but no, viewers know who the killer is in the first ten minutes, or from the box artwork, which is the entire point to this exercise in domestic violence. You know who did it; you keep watching to see how she does it and to whom. The Perfect Nanny isn't perfect, but since viewers already know what they're getting into, it's not terrible either.