James Stewart (who has a severe fear of heights) plays a retired police detective who is hired by a friend to follow his wife whom is supposedly being possessed by the spirit of an insane woman. The detective and the disturbed woman fall (no pun intended if you indeed did see this film) in love then....well, I just can't bring myself to reveal anymore because it will ruin it for all of you who haven't seen it.
I think this movie pretty much defines interesting twist. Completely surprising and a rollarcoaster the whole way through, this is Hitchcock at his strongest. The plot is rivetting, the cast is dazzling and of course bedlam ensues. Everytime I watch this, I find an even higher respect for Hitchy's warped genius.