This was on the Ain't It Cool News list of best horror for last year, I just now got around to watching it on Netflix.
Sun Choke is one of those indie movies where a lot is implied but few things are spelled out. A young woman (Margo...or Janie?) is basically the prisoner of an older woman who has promised Margo's father she would take care of her. The older woman makes her do meditation, take pills, color in pictures of flowers and occasionally punishes her by hitting a tuning fork and saying "Sun Choke" which seems to send Margo into convulsions. When Margo is allowed to leave the house, she almost immediately latches onto another young woman named Savannah and begins stalking her. The halfway point of the movie is the moment where that stalking turns into something else altogether.
This is a hard to watch movie. There are scenes where Margo has infiltrated Savannah's house and is still inside when Savannah gets home where the tension is almost unbearable. There is graphic violence and very non-sexy nudity. When things begin to escalate for our protagonist, I had no idea where the movie was going to go. Where it ends up is kind of ho-hum for the amount of tension and build up that go into it but it is a full narrative. The main question that is never answered is a weird scene that is flashed to once with Margo surrounded by people while she freaks out and I am pretty sure her father is there. We never know the extent of her trauma but trust me, this is one messed up chick.