A PRAIRIE HOME COMPANION — *** — Garrison Keillor, Meryl Streep, Kevin Kline; rated PG-13 (vulgarity).

"A Prairie Home Companion" is Robert Altman at his most Altmanesque. Any desire to see it should be gauged by your tolerance for meandering tracking shots, big, bizarre ensembles and a story that seems to drift on the winds of the hot air blown from the characters' overlapping dialogue.

This review comes courtesy of someone who's a sucker for all of the above, which Altman applies with his masterfully ironic and curmudgeonly eye to a whimsy-filled fantasy about the last night of Garrison Keillor's venerable program.

On the radio airwaves, "A Prairie Home Companion" is still going strong after 30 years. For the big screen, though, Altman and screenwriter and co-star Keillor have imagined a mirror universe, blending real people behind the show with fictional characters who are part of the "Prairie Home" universe — and even weaving in a trippy supernatural element.

The result is an ambling, rambling, folksy yarn that nicely captures the radio-show-that-time-forgot spirit of Keillor's music and comedy revue. It's a suitable companion piece to past Altman forays into the arts such as "Nashville" and "The Player," though lightweight by comparison.

The tremendous cast, including Meryl Streep, Kevin Kline, Lily Tomlin, Lindsay Lohan, Woody Harrelson, John C. Reilly and Virginia Madsen, mixes with an easy camaraderie. It's no stretch to believe that Streep and Tomlin are sisters who have been singing together all their lives or that Harrelson and Reilly are cowboy pranksters who have shared a musical act for years.

And Keillor proves as ideal a master of ceremonies on film as he is on radio.

In Keillor's cinematic take on things, "A Prairie Home Companion" is not a public-radio staple nationwide but an old-fashioned show aired locally in St. Paul, Minn. Except for an epilogue, the film takes place all in a single evening as the show's performers and crew go through crises big and small while putting on a heck of a live broadcast.

Keillor's the host, simply known as GK, a languid gabber who's like a human weather vane, his attention and tall-tale telling switching directions at the slightest provocation.

The other inhabitants of GK's little world are in a tizzy because their radio station has been sold, it's their last broadcast and the building is slated for demolition. But GK shrugs it off and treats it like any other show, fatalistically declaring that every performance is the last.

Keillor's screenplay makes room for a delightful roster of quirky characters.

Streep is Yolanda Johnson, an old flame of GK's who sings sweet, old-timey tunes with sister Rhonda (Tomlin), the siblings sharing happy-sad memories of their departed relations, including two other sisters they once performed with.

Yolanda's daughter (Lohan) hangs out during the show, witnessing the sometimes surreal backstage antics while writing poetry about suicide.

Harrelson and Reilly are Dusty and Lefty, singing cowpokes with a bawdy flair, and Kline plays Guy Noir, an old Hollywood gumshoe who works as the show's head of security (Noir is a fictional character Keillor created on the radio show).

Madsen drifts in and out as an angelic beauty who wanders among the show's cast and crew with a mysterious task to perform, while Tommy Lee Jones pops up as the hatchet man dispatched by the radio station's new owner.

The characters' exchanges are strange, ethereal, heartwarming and often quietly moving; the on-stage theatrics are energetic, mellifluous, corny and often hilarious.

The film uses the radio show's actual setting and house band, while many of the songs originated on the show itself.

Typical for Altman's improvisational style of shooting, the actors hurl themselves into their characters with such fervor that it's almost impossible to pick any standouts. They're all terrific.

The epilogue feels awkwardly tacked on, as though Keillor and Altman didn't really know how to end the film. They might have dispensed with the postscript, since the point of the circuitous film, if it has one, is that endings are always upon us, even when they don't seem like endings.

"A Prairie Home Companion" is rated PG-13 for risque humor. Running time: 105 minutes.