O K . . .
A young girl goes with her boyfriend to visit his family for the first time over Christmas in rural Wisconsin. Once there she meets his mother who takes an instant dislike to her, sensing that she knows her from somewhere. Pretty soon people starts to die and you know where this is going...
No, actually you don't.
People start to die, yes but they are killed by a ghostly samurai who only shows up when the young girl has an orgasm.
And then everything starts to look like an 70s episode of Dr Who, filled with flashing lights and laser effects. I kept expecting Tom Baker to pop up with his giant hair and googly eyes.