And they're singing their lines because

If ever there were a reason that the show was unimaginable as a film, it was this number. How could anything compete with the radiant memory of Holliday's staggering cri de coeur?

Naturally, the question on everyone's mind is how Jennifer Hudson, who plays Effie White in the new "Dreamgirls" movie, comes through in her big moment.

The answer, surprisingly enough, is remarkably well. But more important, the film, directed and adapted by Bill Condon, works because it embraces its own medium and doesn't try to pass itself off as a theatrical production for the multiplexes.

Alan Bennett's "The History Boys," another high-profile stage-to-celluloid transfer this year, has a harder time making the transition. Interestingly, the histrionic classroom scenes in which the boys act old Hollywood melodramas, improvise brothel bargaining in French and sing cabaret torch songs are the most memorable. It's the more straightforward dramatic bits that seem embarrassingly stagy.

Realism in film isn't easy to get around, and movie musicals have the toughest challenge. No matter how you spin it, breaking out into song and dance isn't normal behavior outside of a club, a disco or the privacy of your curtained home. For most of us, launching into a power ballad on the job would probably result in not having one to go back to in the morning.

The first thing the director of a movie musical has to figure out is how to construct a cinematic world in which communicating in music doesn't seem, well, totally nuts. Last year's "Rent" pretended it didn't matter -- that we would accept a documentary-real East Village with denizens erupting, en masse, into rock anthems.

Not quite. Strangely, the stage version didn't even try to get away with that. The Broadway set screamed concert musical, not Alphabet City. The mood was urban, but the address was purely -- and contemporarily -- theatrical.