A superb film script, like a great athlete, makes everyone on a team play at the top of his game.

A director of modest gifts shows fresh insight into his craft. A once-bland hero commands the screen, while a once-dull leading lady glows like marble by moonlight.

All this happens in ``Shakespeare in Love,'' an exhilarating romantic comedy that brings the Elizabethan era to bawdy, bustling life and turns the world's most venerated writer into a very human being. It also exalts the power of theater -- still the world's most potent art when written and performed by masters -- to change our minds, hearts, even our lives.

Marc Norman (who wrote the initial draft) and dazzling playwright Tom Stoppard (who rewrote it years later) are the engineers behind this remarkable machine. Like their title character, they can cram almost every type of emotion into two hours' traffic on screen yet dovetail them neatly.

The time is 1593. The 29-year-old bard (Joseph Fiennes) has writer's block, and for good reason: Seedy impresario Philip Henslowe (Geoffrey Rush) demands a comedy called ``Romeo and Ethel, the Pirate's Daughter.'' Shakespeare wants to write a play as solemn as Christopher Marlowe's ``Doctor Faustus,'' but he satisfies his producer instead of his muse.

At auditions for ``Romeo,'' he's drawn to actor ``Thomas Kent'' -- really Viola de Lesseps (Gwyneth Paltrow), a theater-struck lass who, like all women then, is prohibited from appearing on stage.

``Kent,'' fearful of discovery, runs home; Shakespeare follows and learns her identity. Soon he earns Viola's love and the enmity of Lord Wessex (Colin Firth), the unwanted groom-to-be assigned by her social-climbing father.

Since Shakespeare has a wife, and Queen Elizabeth (Judi Dench) sanctions the Wessex-de Lesseps union, the playwright knows he and Viola share a hopeless passion. It seeps into his writing, elevating ``Romeo'' to tragic grandeur.

Norman and Stoppard, aided by intelligent direction from John Madden, riff away from the central plot like virtuosic jazz musicians.

They use a huge supporting cast, from egomaniacal actor Ned Alleyn (Ben Affleck in a bravura performance) to Hugh Fennyman (Tom Wilkinson), a sadistic moneylender who develops a tender side as he falls in love with theater.

In-jokes flow like ale in a dockside tavern. Shakespeare keeps overhearing phrases and encountering people who'll find their way into his work for years. Marlowe (Rupert Everett) takes pity on him, suggesting not only a new title for ``Romeo and Ethel'' but a change of scene to Italy, where the heroine might have a brother or cousin who disapproves of her lover.. . .

My favorite gag is the street urchin who cavorts with rats and goes to plays only for bloody bits: He likes ``Titus Andronicus,'' where Shakespeare has a villain tear out a rape victim's tongue. The kid is John Webster, who grew up to redefine English theater with gory dramas such as ``The Duchess of Malfi.''

The writers occasionally try sleight-of-hand they can't pull off. I never believed Shakespeare could dance with Viola, then meet her again as ``Kent'' without recognizing her. (And how did Viola's two feet of strawberry blond hair fit under a close-fitting brown wig?)

While truth can be stretched in so noble an effort, Shakespeare was hardly obscure at the time of ``R&J''; he'd written about a dozen plays, many of them hits. He pens ``Twelfth Night'' in a burst of creativity after Viola leaves, but it wasn't really written for another four years. And how could Wessex have tobacco plantations in Virginia? The first British settlers didn't land there until 1607!

Only a churl would let this interrupt his pleasure, especially when the facts get lost in a swirl of sharp swordplay and sharper acting. I especially liked Fiennes' intemperate Shakespeare and Dench's imperious, clever, spiteful Elizabeth.

The revelation was Paltrow, who has approached this level of commitment only in ``Emma.'' Maybe, like Laurence Olivier, she needs a whalebone corset, assumed accent and glued-on mustache to find the heart of a character, changing her interior by changing her exterior first. She has never been less like herself or more appealing.