''It's about a woman who's willing to do everything to get back her lost son,'' says thriller vet director Joseph Ruben (''Sleeping With the Enemy''), whose last film was 1998's ''Return to Paradise.'' ''The only problem is, her son may never have existed, so that's the central mystery of the movie. Did he ever exist? And if he existed, what happened to him? Is she crazy or is the world crazy?''
Unless you're counting ''Hannibal'' (let's not), it's Julianne Moore's first psychological thriller. ''Which is why I was attracted to it,'' she says. ''I was excited by the script right away. You read it and you don't know what's happening. You can't even figure out what kind of movie it is initially. You're like, 'Wait a minute.' And it carries you off in the first 10 pages -- you're like, 'What's going on?' Which was fun. It's really an unusual movie.''
Dominic West, of HBO's ''The Wire,'' plays a guy who teams up with Moore after he starts to think he had a kid that nobody remembers too. The actor landed the part even though there was a mix-up and he missed his original audition for Moore and Ruben. ''I was absolutely furious, and gutted,'' West says. But granted a second chance, he won Moore over. And he relished the part. ''Emotionally it was great -- very harrowing,'' he says. ''Lots of physical stuff, lots of fighting, lots of chasing and being chased and being drunk and being grief-stricken and being in love. It was a nice, meaty role.''
Last month, Ruben spent three days reshooting the finale. ''We're making the ending scarier, more thrillerish,'' he reports from the set. ''And we came up with an amazing moment at the very end of the climax that we want to do in a different way that's going to be extremely spectacular.'' Says West: ''It's very difficult making a thriller these days, after movies like 'Memento' redefined them. Audiences are so sophisticated with thrillers that you have to come out with something pretty amazing, and I'm hoping we have, but we'll know soon enough.''
What's at stake Moore's rep as a studio-movie leading lady could use a quick boost after this year's forgotten ''Laws of Attraction.''