The cinematic equivalent of comfort food, watching "A Prairie Home Companion" is elegiac meditation on Midwestern values and live entertainment. The natural pairing of Missouri-born director Robert Altman and Minnesota's Garrison Keillor yields a movie that's at once joyfully alive and yet also mournful about the passing of a way of life.

Filmed entirely on location in St. Paul, Minnesota, "A Prairie Home Companion" takes place on what could be the final night of Keillor's long-running radio program. Even in a world dominated by television, the show remains vibrant, but a Texas conglomerate has purchased the radio station and is getting ready to close down the Fitzgerald Theater. It could be a sad night, but Keillor and his assortment of regular performers -- with "PHC" veterans like Tom Keith, Jearlyn Steele and the Guys All-Star Show Band playing themselves -- are determined not to look forward and to just put on the best show possible. Among the guests are singing cowboys Lefty (John C. Reilly) and Dusty (Woody Harrelson) and sisters Yolanda (Meryl Streep) and Rhonda (Lily Tomlin), the last vestiges of a musical family along with Yolanda's suicide-obsessed daughter Lola (Lindsay Lohan). Also lurking backstage are the show's security man Guy Noir (Kevin Kline) and a mysterious woman in a white trenchcoat (Virginia Madsen), who may either be the show's guardian angel, or an angel of death.

It's difficult to watch the movie and not think of Altman's masterful career, his health problems over the past decade and the fact that every film could be his last. But the director, whose gift for orchestrating orderly chaos is on perfect display, never allows the film to get morose. Keillor, who wrote the loosy-goosy script integrating many of the popular characters and faux commercials from the radio show, declares, "Every show is your last show -- that's my philosophy" and Altman approaches "PHC" the same way.

With most of the movie shot backstage and on-stage at the real Fitzgerald, Altman indulges in a playful balancing act, working with cinematographer Ed Lachman to dart all around the theater, capturing moments, rather than plot points. Altman's favorite technical tricks -- his love for overlapping dialogue and for seemingly meandering hand-held camerawork -- have been perfectly suited for this kind of behind-the-scenes peek in the past and this is no exception, as he makes the most of his cramped quarters.

Watching Tomlin and Streep work with Altman is a particular pleasure. When they sing, the two veteran performers work in confident harmony and they carry that harmony over into the speaking parts, alternating the leads in different conversations and weaving their words in and out in synch. Harrelson and Reilly also show flexibility on-stage and off, while Kline's work is full of subtle comic touches, both verbal and physical. Such is Altman's gift with actors that he even makes Lohan seem fresh-faced and innocent and he builds the film to a climax in which the occasional pop tartlet makes the most of her thin voice to sing a moving rendition of "Frankie and Johnny." Even Keillor, awkward and hardly ready for tight close-ups, adds to the movie's genial tone.

"A Prairie Home Companion" isn't an ambitious movie for Altman, but rather an intimate gem. It's a warm meditation on a world that once was and a time capsule recording just in case it's never accessible again.