This and 'That Cold Day in the Park' have a fair amount in common with the general claustrophobic atmosphere and mental illness. I suppose it could be prosopagnosia. About halfway in I was ready for her to boil the bunny, but it just kept going!
One of Altman's best & most under-seen films. His only out & out 'horror' film and one of the few he wrote himself. It is one of the most cinematic depictions of schizophrenia in film and it, as others have said, serves as a precursor to Altman's 3 Women. Very well acted by Susannah York & Rene Auberjonois and superbly shot by Vilmos Zsigmond. A very disturbing watch.
One usually doesn't associate Robert Altman with the word "creepy" unless one has seen 3 Women (and one really should), but this schizoid nugget is the closest he came to full-on horror. He clearly had been absorbing Bergman and Japanese horror: the atmosphere is richly weird, playing now-you-see-me games with the camera that are sometimes sophisticated, sometimes a kind of arthouse camp. A worthwhile stepping stone.
A bit heavy handed of an approach to insanity via identity shifts, haunting apparitions, and doppelgänger, yet wildly addictive. There is something about the re-occurring image of wind chimes, as if the madness could lead these delicate instruments to explode at any second. The entire interior of the house, in a majestical landscape, resembles a log that's been halfway burned to a silky gray, a stage of aberration.
Altman attempts to condemn the image's source: if the individual is locus of subjectivity, their unity is unreliable, their control provisional. The film's violence aspires to so many cinematic/subjective assassinations, but a synthesis of terminal constructions, ie Polanski's taut horrors, Bergman's visual psychology, forbids the senselessness of its Apocalypticism, the crisis without end. Wanting, overall.
Susannah York is never less than credible, throwing herself into a very challenging role with courageous and committed abandon. Altman collaborates with York to create an unnerving portrait of mental illness which has never been equaled, but has been endlessly ripped off by lesser directors (Ron Howard). The film is in total sympathy with it's mentally unraveling protagonist as she makes her sad flight into madness.