This is clearly the new film in town to catch! It could so easily have been a self-indulgent disaster of the worst kind — an overblown “home movie” by first-time writer/directors Alan Cumming and Jennifer Jason Leigh, riddled with cryptic autobiography, shot on digital video and starring themselves and their Hollywood friends. Happily, it turns out to be a funny, moving, powerful, wholly involving work — and something of a landmark in the use of digital video. The premise of the film is hardly original; A group of friends with a backlog of personal histories and problems get together for an event of some sort (in this case, the sixth-anniversary celebration of Joe and Sally Therrian). As the evening wears on and tensions increase, tongues loosen under the influence of alcohol and drugs and a great many unpleasant truths make their way to the surface. It’s the stuff that Who’s Afraid of Virginia Woolf? and The Boys in the Band are made of — and this film is very nearly in the same league as those works. If The Anniversary Party doesn’t quite cross over into that realm, it doesn’t miss it by far. Cumming and Leigh play Joe and Sally, a couple whose marriage has only recently been patched up and whose relationship is far from out of the woods. Joe is a clever, self-centered writer with as much luck as talent (he’s not even much interested in movies, but is adapting and directing one of his novels for the screen). He’s also not only prone to bouts of bisexuality, but keeps a former boyfriend and a would-be girlfriend on the sidelines to the extent of having them at the party. Sally is a 30-plus actress whose popularity is slipping and whose talent is in question. (Leigh is especially good in this role and brave enough to include scenes from the film her character is working on, which display the exact kind of overly mannered performance that has marred much of her “real” screen work.) To make matters worse, she finds that the character based on her in Joe’s book will be played by the immensely popular young (variously pegged as 22, 25 and 27, depending on who’s speaking) actress Skye Davidson (a glowingly gorgeous Gwyneth Paltrow), who claims to have idolized Sally the actress since she was a little girl (that’ll win you points with an aging actress!). Naturally, Skye is also at the party. Add to the mix, Sally’s beleagured director (John C. Reilly), his neurotic strung-out wife (Jane Adams), aging actor friend Cal Gold (Kevin Kline) who wants the role of a 28 year old in Joe’s movie, Cal’s “retired” actress wife (Kline’s real-life wife, Phoebe Cates), various hangers-on and the much detested next-door neighbors to whom Joe and Sally are sucking up due to small-scale warfare over their nuisance of a dog, Otis. It’s the perfect mix for the disaster that lurks around the edges of the comedy until it finally erupts into catastrophe when most of the partygoers take Ecstasy. As simple as all this may sound, it isn’t simple at all. Cumming and Leigh have fashioned a screenplay of great depth and subtlety that forces the viewer to pick up the details without feeding them to them. It isn’t a film to be watched inattentively. It requires — no, it demands — thought and emotional/intellectual participation on the part of the viewer. Not only is it a daring work in many ways, but a challenging and rewarding one. It’s a little distracting trying to figure out just how much of the film is literally autobiographical, but that’s also part of what makes the film work: the undercurrent of very near the knuckle truth. Technically, the film is also important as the first feature to be shot entirely on digital video that attempts to capture the look of film. It almost succeeds in its goal. The colors slightly lack the saturation of film and scenes that try to balance interior lighting with exterior lighting (the action takes place largely in a glass-walled house) don’t entirely work, but it’s close enough to suggest a future explosion of digital video works that will allow worthy projects that would otherwise be too expensive to get the go-ahead from studios. The Anniversary Party may be spearheading something very worthwhile in the development of movies, but it’s quite good enough on its own merits to warrant the attention of serious moviegoers.