Tim Robbins' grandly ambitious new film Cradle Will Rock, which recreates the collision of art and politics in the Commie-crazy, Depression-addled '30s, is mainstream in all of the best possible ways. It's hard to imagine anyone not getting swept up in the movie's panoramic storytelling, drawn in by its mostly charming performances and ultimately roused by its provocative ideas.

This doesn't mean that Robbins tries to be all things to all people, a fatal flaw of most directors who try to attract mainstream audiences. Clearly he had a very specific vision in mind for this film, which is theatrical in style and pointedly liberal in its mosaic-like reconstruction of a chapter of American history. Robbins wins us over by playing it fast and loose with material that could easily have appeared dry and familiar, so that the occasional weak link and oversimplification in the film's interlocking web of stories seems irrelevant in the face of so much snowballing enthusiasm.

The heart of the movie is a dramatization of the real-life events behind the renegade production of the 1936 musical play "The Cradle Will Rock," a Brechtian compilation of songs that depicts the workers of Steeltown, USA standing up the Man. Robbins treats the show as an important cultural moment in which the political and cultural tensions of the decade finally bolted to the surface. The facts of the story are all true and fascinating. Blitzstein, played with suitable gusto by Hank Azaria, wrote the words and music for Cradle in a rush of inspiration, fed up with various forms of prostitution in American life. In Blitzstein's reading of the social climate, virtuous girls were compelled to sell their bodies and young men forced to sweat it out in factories while the fat cats leaned back and watched their money grow. Orson Welles (Angus MacFadyen) directed the musical under the aegis of the Federal Theater Project, a government initiative intended to provide work and keep culture going in rough times. But anything approaching Blitzstein's socialist sentiment wasn't welcome as the Red Scare heated up and suspicious eyes turned to the nation's artistic community in order to find a culprit for the spreading virus. Rather famously, Welles' production was shut down on opening night, marking the only time that federal troops were called in to squelch an evening of theater.

But there's much more to the film's story than this one defining event. The movie's opening shot follows the homeless Olive Stanton (Emily Watson) down the streets of New York, then tracks the steps of a nervous, buttoned-down worker (Joan Cusack) tacking up posters for a meeting of anti-Communists, and winds up at Blitzstein's window. Constant life emerges from the movie's seams as Robbins populates his film with a dizzying roster of figures from the era.

So we are also treated to the story of Hallie Flanagan (Cherry Jones), the passionate director of the Federal Theater, who is called in to testify in front of a Congressional committee which labeled Euripedes and Christopher Marlowe as Communists. (Most of the great, crackling dialogue in these scenes is taken from actual court records.) We get to see Stanton, played by Watson with a sweet voice and eyes that beam happily for once, step off the streets and into the lead of Blitzstein's play. A giddy socialite (Vanessa Redgrave) departs from the conservative wishes of her husband, publishing giant William Randolph Hearst, to join the theatrical cause. Italian journalist Margherita Sarfatti (Susan Sarandon) tries to make Mussolini's fascism palatable to American industrialists through artistic exchange. And so on.

Told alongside all of this energetic hoopla is the story of Nelson Rockefeller (John Cusack) and his patronage of the Mexican muralist Diego Rivera (Ruben Blades), providing another example of the complex problems that can result when artistic statement is bound to a controlling force. Young Rockefeller didn't count on Rivera painting Lenin and syphilis cells in the lobby of Rockefeller Center, so he orders the mural jackhammered off of the wall in a strikingly literal expression of the casual tyranny of commerce. Yet perhaps the most poignant thread of the film is its only fictional tale, that of an aging ventriloquist (Bill Murray), who, with the help of Joan Cusack's rabble-rousing character, turns against the Federal Theater when he suspects Communist influence. He later comes to regret sacrificing his art when, with sublime irony, his own dummy turns against him.

Robbins' history lesson never feels spoon-fed, delivered with a snappy pace and comedy that is by turns broadly slapstick and subtly incisive. Nimble performances keep this complicated creation afloat. Though the film's scope makes all of its portrayals into caricatures, the actors seem aware of the limitations of their parts and do their best to bring them to life in quick, bold strokes. Among the most remarkable are Cherry Jones, whose tough-talking moll displays a deep belief in the power and necessity of the theater, and Ruben Blades, who melts into his small role as Diego Rivera in a perfect impersonation. John Turturro shines brightly as Aldo Silvano, a dedicated member of the "Cradle" cast who parts ways with his family of Italian nationalists. John Cusack is effective as the affably cocky Rockefeller, and Bill Murray and Joan Cusack hit both comic highs and notes of genuine sadness. Less successful are Vanessa Redgrave, who's garishly over the top, and Susan Sarandon, who acts mostly with her eyebrows and strained Italian accent. As Welles, MacFadyen is boorish and obnoxious, and Robbins has already been chastised by some for so pervasively emphasizing the famous director's hamfisted side.

The film's one-note Welles is a manifestation of a certain mindset that Robbins imposes in the movie's weakest moments, in which the characters expound so directly about art, politics and historical issues that they momentary sacrifice credibility. But the subtler portrayals dominate, and Robbins' direction keeps the multitude of stories on track, heading toward a finish that is more than dynamic and complex enough to justify earlier moments of simplification.

By the time film reaches its triumphant conclusion--a spontaneous, bare bones production of Blitzstein's musical, in which all of the cast risk their jobs with the Federal Theater for the sake of a single performance--Robbins' purpose in embracing the subject is both abundantly clear and difficult to refute. The movie suggests that the artistic quality of Blitzstein's work (which, from the bits represented here, seems questionable) matters less than the fact that it was performed. The final, unexpected shot of the film says in no uncertain terms that its message isn't limited to history. Cradle Will Rock reveals Robbins' rare talent for making accessible entertainment that never compromises its vigorous commitment to ideas.