In "A Prairie Home Companion," genial host G.K. (Garrison Keillor), left, and the singing Johnson sisters, Rhonda and Yolanda (Lily Tomlin, Meryl Streep), finally get the chance to welcome Yolanda's formerly surly daughter Lola (Lindsay Lohan) to the radio show.

Talk about being on the same wavelength.

For more than 30 years, Robert Altman has woven insightful cinematic tapestries, from "M*A*S*H" to "Nashville" to "Gosford Park."

And for more than 30 years, Garrison Keillor has spun sly, homespun tales for millions on his weekly public radio variety show, "A Prairie Home Companion" -- including Las Vegans listening in on KNPR-FM 88.9.

As native Midwesterners and natural storytellers, Altman and Keillor also turn out to be natural-born collaborators.

And their initial collaboration, "A Prairie Home Companion," turns out to be a definite cause for celebration.

A beguiling backstage fable with a dream cast, "A Prairie Home Companion" offers a hilarious -- and heartfelt -- valentine to radio.

Specifically, the folks at the Fitzgerald Theater in St. Paul, Minn., scrambling to produce another weekly radio broadcast.

Change is in the air, however, signaled by the presence of an angelic visitor (Virginia Madsen) and a much-less-angelic Texas tycoon (Tommy Lee Jones), whose conglomerate has just gobbled up the show's radio home.

But the "Prairie Home" companions can't worry about any of that. Not with a show to do.

Which means singing sisters Yolanda and Rhonda Johnson (Meryl Streep, Lily Tomlin) warbling on about "My Minnesota Home" despite the doom-and-gloom antics of Yolanda's moody teenage daughter Lola (Lindsay Lohan).

OId Trailhands Dusty and Lefty (Woody Harrelson, John C. Reilly) sing and strum, whether the topic happens to be "Git Along, Little Dogies" or "Bad Jokes."

Dapper detective Guy Noir (Kevin Kline), meanwhile, keeps a keen eye out for suspicious characters -- and, alas, not so keen a watch for backstage slapstick hazards. And harried host G.K. (none other than Garrison Keillor himself) struggles to keep the show running despite obstacles onstage and off.

Throughout, Altman's mastery of visual, verbal and musical storytelling keeps the movie gleefully in tune, bringing to life radio's mind's-eye magic with gentle warmth and irrepressible, irresistible humor.

In such exemplary acting company, Keillor seems understandably overmatched -- even playing a self-deprecating version of himself.

Otherwise, "A Prairie Home Companion's" cast could hardly be better -- whether it's Harrelson and Reilly's wry folksiness, Lohan's deft deadpan or Kline's matchless blend of suave klutziness.

As you might expect, however, Streep and Tomlin steal the show with a perfect balance of quirkiness and poignancy.

Come to think of it, that also describes "A Prairie Home Companion" as a whole.

But if you prefer a more succinct summary, here's a two-word conclusion: Tune in.