Alan Cumming and Jennifer Jason Leigh are a couple struggling to hold onto their marriage in The Anniversary Party

Jennifer Jason Leigh and Alan Cumming (who also wrote and directed the picture together) play Sally and Joe. He's a successful novelist who has just been tapped to adapt his latest book for the big screen. Joe has never written a screenplay or directed a film before, so the challenge is daunting. The book was inspired by his own relationship but Sally, a famous actress, is not even a consideration for the role that is based on her. She is, quite simply, too old to play the character. This is a source of much consternation, especially considering that Joe invites young star Skye Davidson (Gwyneth Paltrow) to the party in hopes of luring her into the role.

Other attendees include the director of Sally's new movie, Mac Forsyth (John C. Reilly), and his neurotic wife Clair (Jane Adams), her current co-star Cal Gold (Kevin Kline), and Joe's photographer friend Gina (Jennifer Beals) whom he turns to in times of crisis. As in all "party movies," the characters mingle with one another, eventually revealing a tapestry of resentments, jealousies, and secrets. For example, Mac reveals that Sally is turning in a lame performance in her new movie, a sentiment that Cal backs up. Making that problem worse is that Sally is jealous of the younger, sexier Skye. For advice, she turns to her best friend - and Cal's wife - Sophia (Phoebe Cates), but the resulting pep talk is more of a let-down than a pick-me-up. Joe, one the other hand, faces constant fear of failure. He feels tremendous pressure to prove two things: that he can make a movie and that he can stay faithful to Sally.

There is also a very funny subplot involving Joe and Sally's dog Otis, who is accused by the neighbors of barking all the time. The neighbors are invited to the party as a gesture of "sucking up" after a series of hostile words that have been exchanged. However, the two couples soon discover that they have nothing to talk about except the dog.

Watching The Anniversary Party is like really being at Joe and Sally's celebration. And the overwhelming feeling you get is this: everyone in the room is worried that the couple won't last. Sure, they all offer platitudes about how wonderful it is that Joe came back. But deep down, everyone's afraid. That feeling is crucial to the movie. Each scene, each interaction between characters has a weight to it. The wrong remark by one person could create a cataclysmic effect for someone else. Certain characters are alone in a room with other characters and you almost dread what they might say to one another. Imagine attending a fabulous party in which everyone is witty, interesting, and not on their best behavior. Add a couple hits of the drug Ecstasy. Throw the metaphorical pink elephant into the middle of the room, then sit back and people-watch. That's the effect of this movie.

Although Joe and Sally are the core figures, every member of the ensemble cast gets the chance to create a 3-dimensional character. Leigh and Cumming have cast their friends in roles, and sometimes the characters play off the real-life traits and public personas of the actors themselves. For instance, like their characters, Kline is a top Hollywood actor married to a former star-turned-full time mom (And let me interrupt myself to bless the filmmakers for dragging Phoebe Cates out of retirement. She gives a stellar performance that deserves Best Supporting Actress consideration.) Paltrow sends up her possibly- unfair tabloid image of the young ingenue who calculates every move of her career. Because the actors are playing skewed versions of their own personas, the characters manage to develop fully even in very short amounts of screen time.

The Anniversary Party takes place over a 24-hour period. Consequently, there are no easy answers. But this is not a movie about answers. It's about questions. How do two people who are desperately in love with one another survive the adversity of their different career paths? How do they hold on to that love when one of them has committed an act of betrayal? Who do they confide to about each other? How do you keep the faith in your marriage when all your friends feel it won't last? The Anniversary Party is like watching a great exercise in social psychology - funny, surprising, fascinating. I couldn't take my eyes off it.

( 1/2 out of four)

The Anniversary Party is rated R for language, drug use, and nudity. The running time is 1 hour and 55 minutes.