Sweeney's magical makeover

At a screening of Sweeney Todd in Leicester Square just before Christmas, Stephen Sondheim stood up in his well-worn grey sweater and advised the forty-odd invited friends not to waste time making lists of what was missing from the show, "or you're not going to enjoy it at all".

At four minutes under two hours, Tim Burton's movie is more than a third shorter than the stage musical and unadorned by any pedigree singer or torch-song. Sondheim, a hawk-eyed perfectionist who labours long and late over the scansion of every last syllable, had turned over his finest work to the gothic slashers of Hollywood to do with as they would. He took no active role in the adaptation yet, strangely, he seemed pleased with the result.

"Think of it," smiled the composer, "as a movie. Don't think of it as a musical." Two hours later, that distinction was resoundingly confirmed. Burton's spartan reduction unfolds the tale as a Victorian epic in which good and evil interplay in the cesspit of a London that, with its slippery culinary fashions, could just as easily embrace celebrity cannibalism in our time as it did in Sweeney's. Todd, returned from penal exile, is out to wreak vengeance with his barber razors on the city that sent him down and the judge who raped his wife and stole his daughter.

The narrative is ruthlessly linear, all digressions excised. This is a tale of obsession, of love and pain and fear and loss, the heart tugged towards the throat-slitting barber (played by Johnny Depp) and his plump accomplice Mrs Lovett (Helena Bonham Carter), who turns his victims into succulent man-meat pies. Burton adopts a monochrome scenography, reminiscent of his ghost-horror Sleepy Hollow, to detach us visually from the protagonists even as he deepens our emotional investment in their fate. As a piece of storytelling, Sweeney Todd the movie struck even the inner circle of Sondheim purists as a remarkable reinvention.

After the screening, cup of tea in hand, Sondheim himself made a claim so extravagant that I had to ask him to repeat it. "This," he declared, "is the first musical that has ever transferred successfully to the screen."

Before you attempt a contradiction, remember that Sondheim speaks as one who knows. He was Oscar Hammerstein's semi-adopted son, accompanying his trail of triumph from Oklahoma! to The Sound of Music, and Leonard Bernstein's lyricist on West Side Story. Yet Sweeney Todd, in Sondheim's quiet, non-hyperbolic opinion, is the first successful movie in the pack. What are we to make of that?

In strictly categorical terms, he's right.

West Side Story, in common with most Broadway transfers, feels decidedly stagy on screen. And even the wide open beaches of South Pacific and Hitler's favourite mountain peaks at Berchtesgaden cannot disguise the suspensions of plot when someone has to wash a man right out of her hair or teach seven children a diatonic do-re-mi.

At those moments, the craft of movie-making gives way to crowd-pleasing show-stoppers and the story grinds to a halt. In Tim Burton's Sweeney Todd, there is no such respite - not even to include the delectable Kiss Me quartet. It is pure movie, so much so that two young members of the mostly British cast - Jamie Campbell Bower, who plays Anthony, and Ed Sanders (Toby) - told me they had avoided seeing the show or listening to soundtrack recordings in order to approach the movie as an original work. Similarly, Sacha Baron Cohen as Todd's rival barber Pirelli gives no sign of playing off previous actors' cameos; his role is freshly created for the screen.

Sweeney Todd the musical is, of course, famously indestructible. I have seen it raise the roof at the Royal Opera House and in half-rehearsed college productions, with full choreography and in John Doyle's compact version for nine singing instrumentalists. Sweeney never fails. Getting it on to screen, though, was fraught with obstacles. Sam Mendes, who acquired the rights in 2003, confessed after two years that he could not find a way of staging it without stopping for musical set-pieces - which screenwriter John Logan did not want.

Tim Burton, who first showed interest a decade ago, stepped in with an irresistible billing of his close friend Johnny Depp and his pregnant wife, Helena Bonham Carter. Both could do authentic cockney accents, but neither had sung before. Expecting a semi-spoken declamation, Sondheim was surprised to find that Depp and Bonham Carter had pleasant mid-range voices and good rhythmic sensitivity. The impassivity that Depp sustains so well in his most celebrated roles was ideally suited to Sweeney's enigmatic morality and the rest of the cast - topped by Alan Rickman as the villainous judge and Timothy Spall as his beadle - formed a heaven-sent, Radatrained ensemble.

Whether the movie fulfils Sondheim's hope of reaching a multiplex audience that never enters the living theatre remains to be seen, hamstrung as it is by a ridiculous R rating in the US, limiting admission (on grounds of violence) to over-17s, followed by a doubly absurd 18 limitation in knife-culture Britain.

That constraint, though, is already being mitigated by YouTube clips that are reaching millions and by a swell of industry whispers that predict a bumper crop of Oscars at the coming awards. Is this then, as the composer claims, the first stage musical ever to make a successful switch to the movies? After several weeks' reflection, I'd go one further: I cannot recall any modern theatre play - by Pinter, Miller, O'Neill, Albee, Neil Simon, whoever - that has made the leap to screen carrying so little of its stage baggage while its character remains intact. Sweeney Todd is a gripping, skilful, troubling, ineradicable masterpiece of a 21st century movie. All that came before is gaslight.

Sweeney Todd, The Demon Barber of Fleet Street opens on 25 January; the soundtrack is out now, on the Nonesuch label.