Calling itself "a (mostly) true story," "Cradle" uses its impressive ensemble cast to confidently intercut characters playing out a fistful of stories over an eight-month period from the fall of 1936 through a legendary performance of the Marc Blitzstein musical on June 16, 1937, that gives the film its name.

As a Robert Altman-influenced kaleidoscope of interlocking scenarios--some true, some exaggerated, some completely made up--"Cradle" has more energy than sense at times, and its passion for screwball farce is not always welcome. But its fidelity to the tenor of the times as well as its nervy decision to cut as wide a swath as possible through one of the most exciting and meaningful periods of our history have created something that's impossible not to both applaud and enjoy.

This is Robbins' third film as a writer-director (after "Bob Roberts" and "Dead Man Walking") and as a group they reveal a rare gift for making serious material completely accessible. What Robbins has been understandably attracted to here is a moment in time when artists were socially conscious and they were proud their work was known as committed and political.

Blitzstein's play (full title "The Cradle Will Rock"), described as the first American musical about serious issues, fits that scenario snugly. Set in the mythical Steeltown, it follows a union struggling against the power of ruling capitalist Mr. Mister. We see Blitzstein (Hank Azaria) composing the musical under the spell of both his dead wife and a still-living Bertolt Brecht, who tells the writer not to forget to include "an artist or two. They are the biggest whores."

Blitzstein's is only one of the many stories "Cradle" follows, almost too many to even list. Here's young Nelson Rockefeller (John Cusack), sparring with Mexican artist Diego Rivera (Ruben Blades) over a mural commissioned for Rockefeller Center. And there's the real-life Margherita Sarfatti (Susan Sarandon), described by Rivera as "the publicity queen for the new Roman Empire," trying to get industrialists like fictional steel magnate Gray Mathers (Philip Baker Hall) to offer tangible financial support to the Mussolini regime.

Most of "Cradle's" drama involves the Federal Theater Project (an offshoot of the New Deal's Works Progress Administration), an enterprise that reached 25% of the American population and was as close as this country ever came to having a genuine national theater.

Cherry Jones, a superb Tony-winning stage actress, gives her most impressive screen performance to date as Hallie Flanagan, the woman who ran the Federal Theater Project. Jones' controlled energy and charisma simultaneously drive the film and ground it in a reality it needs, and her's is the one performance that stands out in a very accomplished crowd.

Flanagan's most high-profile producing/directing team are John Houseman (Cary Elwes) and Orson Welles (Angus Macfadyen), already old hands at the bickering collaboration that would end up animating the Mercury Theater. They are putting on Blitzstein's "Cradle," a production that also employs fictional actor Aldo Silvano (John Turturro), having trouble with his proto-fascist family, and the real-life would-be actress Olive Stanton (Emily Watson), down on her luck and hoping for a chance at a real job.

All this is happening under the malignant shadow of the Dies Committee, a congressional precursor to the House Un-American Activities Committee that is preparing to hold hearings about the presence of communists in the Federal Theater Project.

Cheering the committee along is the humorless Hazel Huffman (Joan Cusack), a worrywart vigilante who fears the Red Menace. And cheering her on is Tommy Crickshaw (Bill Murray), a proud but sour ventriloquist whose main beef about communists is that they're just not funny.

Though Murray is brilliant as always and convincingly antediluvian, "Cradle's" more obvious attempts at humor do not come off. Especially irritating is Vanessa Redgrave as madcap social butterfly Countess La Grange, the wife of steelman Mathers, whose protege Carlo (Paul Giamatti) is nowhere near as amusing as the Preston Sturges character he seems a knockoff of.

Willing to move mountains to make its points, "Cradle" squeezes together into its eight months events that were years apart: the Rivera-Rockefeller conflict goes back to 1933, and Hallie Flanagan's Dies Committee testimony didn't happen until 1938. More troubling than this minor date switching is the way poor Marion Davies, in reality one of the true talents of the silent screen, is yet again (this time played by Gretchen Mol) maligned as no more than the dumbbell mistress of William Randolph Hearst.

But quibbling with a film this enterprising is really beside the point. As a mixture of drama, humor and history, a melange of seriousness and slapstick, real people and imagined characters, it definitely stands out. This is our history, and it's good to have it back again.

* MPAA rating: R, for some language and sexuality. Times guidelines: rough language and a few snippets of nudity.