Long before "Tootsie's" Dustin Hoffman was even a twinkle in an ancestor's eye, William Shakespeare was already dealing with mistaken sexual identities and misdirected passions in "Twelfth Night."

Despite its popularity on stage, the Shakespearean comedy has never turned up on the big screen - its most famous incarnation to date has been a very memorable version for BBC television featuring Alec Guinness - although why not is anyone's guess.

Maybe the project was just waiting for Trevor Nunn, artistic director of the Royal Shakespeare Company. Aided by a cast of British stage veterans and character actors, Nunn has done a very good job of keeping the humor and vitality of Shakespeare intact, even though he has changed its time-frame to the 1890s.

Its timing certainly couldn't be better, as this very good and funny version of "Twelfth Night" should help to wash the unpleasant taste of last year's MTV-inspired "William Shakespeare's Romeo & Juliet" out of our mouths and to whet our appetites for Kenneth Branagh's upcoming film version of "Hamlet."

As the film begins, a ship carrying twin performers Viola (Imogen Stubbs) and Sebastian (Steven Mackintosh) is wrecked off the coast of Illyria. While Viola is saved by the crew, her brother is apparently lost at sea.

Illyria is ruled by Duke Orsino (Toby Stephens), who has been thwarted in his attempts to woo Olivia (Helena Bonham Carter), a young countess who is also in mourning for her own brother. Consequently, Orsino hasn't made the country exactly hospitable for women.

In order to survive, as well as to make an odd tribute to her broth-er, Viola adopts the identity of Cesario and enters Orsino's service. As it so happens, the Duke takes a shine to the lad/lass and sends him to woo Olivia on his behalf.

However, Olivia isn't moved by by the Duke's attention and instead becomes attracted to Cesario, his young messenger, who, in turn, has become overly fond of her master. To further complicate things, Sebastian has actually turned up on Illyria and is heading for a direct collision course with Viola/

Cesario.

Meanwhile, Olivia's boisterous, drunken uncle, Toby Belch (Mel Smith) has made a mess of her household and has even entered a bitter household struggle with Malvolio (Nigel Hawthorne), her self-righteous steward.

Things aren't nearly as confused or confusing as they sound, and Nunn wisely presents them in a very light, almost flimsy manner. Of course, he's helped by a wonderful cast, especially Bonham Carter, Hawthorne and Ben Kingsley, who shows off a quite decent singing voice as the film's sort-of-mystical narrator.

And despite the non-convincing nature of her disguise - a flimsy moustache and more boyish haircut - Stubbs has more than enough charm to pull off her very difficult role. Besides, were any of us really convinced that Hoffman looked like a woman in "Tootsie?"

"Twelfth Night" is rated PG for violence, mostly swordfighting and fistfights, and some mildly vulgar references and sexual innuendos, as well as glimpses of a nude statue.