Flirts with the sexual ambiguity of the father-daughter relationship. A mysterious letter left by her dead mother to be opened only upon her father's death disinhibits the daughter's Electra complex. The father, of course, is complicit in its opening. The movie, deliciously slippery and sly, matches its playful ambiguity to that of its subject matter; appearances are skillfully manipulated, realities shift. The friendly sexual antagonism is the female counterpart to the Oedipal hostility of Polanski's Knife in the Water.
Like the artificially notched-up conflict in III, there's a long unconvincing scene of direct confrontation between father and daughter at the heart of the movie that would have been better toned down or left out; the daughter's acting lessons similarly could have been deleted or minimized (we don't need to be told about subtext); both are too expository, too obvious, and detract from the momentum. Intrusive symbolism takes the form of a man repeatedly seen carrying a white diamond-shaped punt, i.e., for all intents and purposes a cross, which I found inadvertently funny. I thought the plot reversal near the end ingenuous; others have complained. After all, the letter and its contents are trivial compared to what they represent psychologically. It's a tease.