John Cameron Mitchell's new film "Shortbus" is at once the sweetest and the most openly sexual - really and truly open and really and truly sweet - film I can recall seeing. The title comes from someone's calling schoolbuses the 'long one' for all the regular students, and the 'shortbus' for the disabled, dysfunctional, special-ed kids, which Mitchell has used here as the name of a sex-and-party club somewhere in Williamsburg, across the bridge from Manhattan.

Mitchell's last film was "Hedwig and the Angry Inch," that fascinating, touching, and completely original work which used the framework of a musical comedy to tell the story of a man who had had his penis cut off except for one 'angry' inch. "Shortbus" shows another side of Mitchell, who worked for two years with his cast to pull it together. The film follows three people - James and Jamie (Paul Dawson and P J DeBoy), a gay couple, and Sofia (Sook-Yin Lee), a couples counselor/sex therapist. James and Jamie, who've been together five years, are tempted by visions of greener pastures, and are dealing with the first fantasies of 'opening up' their relationship to someone - anyone - else; while Sofia, their therapist, is still looking for her first orgasm (she tells them that she's pre-orgasmic; Jamie asks if that means she's about to have one). They are in fact three of the sweetest people you'd ever want to meet. There's even a fourth, a dominatrix named Severin (Lindsay Beamish) who's sick of dominating and yearns for another line of work.

They all find their way to the Shortbus, where couples and groups and individuals of all kinds and genders are having, well, a ball. There is more naked, open sex in the film than in even the best-populated porn film; it is, however, sweeter, more loving, and certainly more fun than porn, because we can see that people are simply having a good time, including giving a performance of "The Star-Spangled Banner" that you are unlikely to see anywhere else. There's even an old voyeur, who 'used to be mayor of New York' - and no names, please - at the club, which is run by a transvestite ringmaster (Justin Bond), who keeps things warm and friendly and sexy.

"Shortbus," like many films frank in their depiction of sexuality, is not likely to get many theatre bookings in the United States, but when it's released on DVD I think you'll have a very good time watching it.