Of course, Catherine was just as campy in the first film, but the whole movie was so over-the-top she blended right in. That film was directed by Paul Verhoeven, a pioneer in excessive sex and violence. And whether his films work (Robocop) or really, really don't (Showgirls), at the very least they're never boring. But with this sequel, director Michael Caton-Jones makes the mistake of keeping the proceedings as serious as possible, which makes Catherine stand out as a cartoon character in a dull police procedural.
The film opens in London, where Catherine fools around with a soccer player in her car at 110 mph. She drives off a pier and survives, but the footballer, having been drugged, drowns. The police suspect foul play and have her analyzed by therapist Michael Glass (David Morrissey), who concludes that she suffers from risk addiction. Catherine then decides that manipulating her new therapist might be just the risky fix she needs, and so begins the predictable dance of seduction. In the meantime, everyone in Glass' life begins to fall prey to mysterious murders.
Since Stone plays the shadowy villain, the unenviable task of carrying the film falls on Morrissey, who has essentially the same role Michael Douglas had in the first film. This time it's the shrink who shouldn't sleep with his patient rather than the detective who shouldn't sleep with his suspect. But where Douglas played the role with hotheadedness, Morrissey plays it with dull stoicism. Even later in the film, when things begin to heat up, Glass maintains a level of stiffness (and not the kind Catherine wants). She and Glass have no chemistry whatsoever, which efficiently removes the eroticism from the erotic thriller.
That leaves the thriller part. But there isn't a shred of suspense in Basic Instinct 2. The final shot of the first film proved that Catherine is indeed a murderer, so we know she's guilty here, too. There aren't even any other possible suspects until late in the second act, when we're thrown an obvious red herring. And some moments, as when Catherine attempts to wake the drowning soccer player, are meant as ambiguities to keep us guessing, but come across as irritating inconsistencies.
Then there's the ending. Massive spoilers follow, but read on anyway. After Catherine has been established as the only possible killer, the film shows us alternate versions of earlier scenes that suggest that Dr. Glass, himself, might be the culprit. It's as though the film is saying, "Aha! You were sure Catherine was the murderer, but if you ignore established alibis and assume that pivotal scenes were lying, you'll find that Glass is, in fact, the true murderer ... maybe." It's a twist with no setup that actually contradicts what we've seen. And it may or may not have even happened! It's quite possibly the most offensive cheat ever shoehorned into a weak thriller.
If you have any basic film-going instincts, you'll avoid this sequel-that-never-should've-been and watch some late-night soft-core porn on Cinemax instead. It'll probably have a better story.