Didn't see THAT coming...(NOT!)
SPOILERS
I think you basically have this plot pegged when there's the obvious closeups of the distinctive hands of the woman being interviewed in the "documentary"....they just really leap out. (And why would a gritty documentary have closeups of someone's hands in it, anyway? The rest of the footage in it doesn't have editing like that.)
This movie falls into the Double Jeapordy class of dumb, cheesy thrillers. Only it's not as well photographed.