Shrouded in a fog of madness, creepy-crawly mental patient Spider (Ralph Fiennes) tries to unravel the tangle of events that led to his father murdering his mother (Miranda Richardson) when he was a wan, wide-eyed child. At the end of Spider, the rug is pulled out and the neat tricks -- intellectual, thematic, dramatic, and otherwise -- are revealed. Though still one of our most interesting directors, David Cronenberg remains mired in the lovingly photographed grotesque; one gets the feeling that his films would be best exhibited under a circus tent. EXTRAS Slight. A Cronenberg commentary, three mildly revealing making-of featurettes, and the ubiquitous -- and always annoying -- ''bonus trailers.''