I guess you're supposed to pick up on Crawford's delusional psychosis during a few scenes in the film, but it's never very firmly established. The tension, however, between her and Van Heflin is pretty good; he's an up and coming engineer and certainly not going to commit himself to her, a clinging neurotic who's a nurse for the suicidal wife of Heflin's employer played by Raymond Massey. When they fish Massey's wife's body (you never see her, but here her voice on the intercom) out of the lake the film hits a dramatic point, and Louise (Crawford) is confronted with Heflin's presence in several great scenes that are full of tension. Things come to an emotionally exciting culmination when Heflin decides to marry Crawford's step daughter played by Geraldine Brooks, which is the last straw for Crawford. It's hard to buy into her being completely crazy and stumbling around in LA and locked up in a psycho ward, especially if you saw the smile on her face when she pulled the trigger not once, but two times in a chilling scene.