This is a very difficult movie, and it's almost impossible to get a handle on what's going on. At first it seems to be a rather pedestrian movie about a guy (Trelkovsky) who needs an apartment and rather crassly invites himself into one when the current tenant (a woman) commits suicide. Then the twists and turns start. Are the neighbors trying to kill him? And why are the dead tenant's clothes turning up in the apartment? One wonders, finally, if Trelkovksy _is_ the prior tenant.
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One of the tricks Polanski pulls on us is to lie to us. We assume when we see things from the point of view of a character that we see things as the character does and that there may be distortions of reality. We assume when the camera is showing us things from its omniscient point of view that we see actuality - but Polanski has the camera lie to us.

Witchcraft/Witchery/La Casa 4/ and whatever else you wish to call it. How about..Crud.
A gathering of people at a Massachusetts island resort are besieged by the black magic powers of an evil witch killing each individual using cruel, torturous methods. Photographer Gary(David Hasselhoff)is taking pictures for Linda(Catherine Hickland whose voice and demeanor resemble EE-YOR of the Winnie the Poo cartoon), a virgin studying witchcraft, on the island resort without permission. Rose Brooks(Annie Ross, portraying an incredibly rude bitch)is interested in perhaps purchasing the resort and, along with husband Freddie(Robert Champagne, who is always ogling other women much younger than him), pregnant daughter Jane(Linda Blair)and grandson Tommy(Michael Manchester, who just looks bored throughout, probably wanting to watch Sesame Street instead of starring in this rubbish), go by boat to the resort being treated to a look at the property by Realtor Tony Giordano's son Jerry(Rick Farnsworth), obviously a pup in the business getting his feet wet. Along with these folks is architect Leslie(Leslie Cumming, whose character is a nympho)who might help Rose re-design the resort. The boat's captain is killed by The Lady in Black(Hildegard Knef, wearing her make-up and lip-stick extra thick)and a storm is brewing. The boat drives off by itself(..guided by the invisible power of The Lady in Black, I guess)with everyone stuck in the decrepit resort, which is in dire need of repairs. Most of the victims, before meeting their grisly fates are carried through a type of red wormhole whose vortex leads to another dimension(..perhaps a type of hell or something)where they are tortured by these fiends dressed in raggedy clothes with a crummy visage. One victim has her mouth sown before being hung upside down in a chimney, roasted as the others light the fireplace. One poor soul is tortured by harsh twistings of rope wrapped tightly around her flesh before being found hanging from the snout of a swordfish penetrating through her neck. One fellow is slowly suffocating as his veins bulge(..and bleed) and neck's blood vessels burst squirting in Hasselhoff's face! One fellow is crucified with nails hammered into his hands before being hung upside down over an open flame. Blair's pregnant victim becomes possessed with her hair standing on end speaking in another woman's voice. One is raped by this demonic man with a "diseased" mouth as the hellish hobos stand nearby gleefully cheering. The film, despite it's excesses, is mostly dull fodder for those who really wish to see the lowest point in the careers of Hasselhoff and Blair, who deserve better than this. Almost unbearable at times, building little-to-no suspense. Clumsy execution of the death sequences which look cheap and laughable. Sure some gore is okay, but most of the film shows victims after they've been run through the ringer. We do get a chance to see pregnant women(..who look exactly like stuntmen in costume with bad wigs) jumping out three story windows. Oh, and The Lady in Black's reflected face often pops up on inanimate objects for characters to see. Tommy has a little Sesame Street recorder which tapes The Lady in Black's mumbo jumbo chants, obviously used for later. For some reason, The Lady in Black likes to visit little Tommy. He's not at all scared of her, for Tommy's just too bored to show any expression on his face, much less fear. Need I say more? This one's a real stinker. Ugh.