An adaptation of the 1979 Tony Award-winning musical by Stephen Sondheim and Hugh Wheeler, "Sweeney Todd: The Demon Barber of Fleet Street" victoriously cuts and thrashes to life on the big screen. In his most bravura directorial effort in over a decade, Tim Burton (2005's "Charlie and the Chocolate Factory") proves that he was born to make this film. Instead of merely helming an unoriginal copycat of the Broadway show, Burton and writer John Logan (2004's "The Aviator") have stayed relatively faithful to the original source material while branching out its energy, scope and haunting deviance in a way that the limits of a stage cannot. There is no denying that this is, indeed, Burton's motion picture, a visually astonishing and imaginative retelling with a Grand Guignol sense of the macabre crisscrossing with a narrative vibrantly told mostly through the power of Sondheim's music and lyrics.

Fifteen years ago, Benjamin Barker (Johnny Depp) was torn from his beloved wife and infant daughter, sentenced to imprisonment by the crooked, conniving Judge Turpin (Alan Rickman), who wanted Benjamin's family for himself. Now finally returning to his old home in 19th-century London, Benjamin has been born a new man calling himself Sweeney Todd. Out for revenge against the man who wronged him, Sweeney is taken in by lonely meat pie maker Mrs. Lovett (Helena Bonham Carter) and sets up a makeshift barber shop above her eatery. As his madness turns to murder, and then cannibalism—he cuts the throats of his clientele, whose meat subsequently reinvigorate Mrs. Lovett's pies—Sweeney moves ever closer to his number-one target, a louse who unforgivably stole his life while, as it turns out, raising long-lost daughter Johanna (Jayne Wisener) as his own.

It is rare for a film to achieve a feeling of unequivocal, breathtaking transcendence, but "Sweeney Todd: The Demon Barber of Fleet Street" does just that. Told almost entirely via song and image, the story's developments extraordinarily unveil themselves in sequences that bleed seamlessly into one another with nary a moment of downtime or choppiness in sight. The editing by Chris Lebenzon (2006's "Eragon") holds an assured fluidity, so much so that the picture approaches qualification as a classical operatic tragedy, while the sparse but successful bids at humor are appropriately as black as the charcoal skies of Burton's London cityscape.

The soundtrack, boomingly reorchestrated by Jonathan Tunick with a ceaseless potency and grandeur that only the cinema can withhold, is marvelous. The musical numbers accompanying them are equally forceful and alluring, each set-piece an aesthetic and aural tour de force. Of these, highlights include "Pirelli's Miracle Elixir," which introduces the characters of Signor Adolfo Pirelli (Sacha Baron Cohen), a haughty, blackmailing salesman who becomes Sweeney's first victim, and orphaned boy Toby (Edward Sanders), an unwitting accomplice of Sweeney's and Mrs. Lovett's dirty deeds; "Epiphany," wherein Sweeney decides that the whole of London deserves a nasty end and takes to the streets to draw in customers to his barber shop; "Johanna (reprise)," in which the purity of young, starry-eyed Anthony's (Jamie Campbell Bower) love for Johanna is intercut with a montage of Sweeney's out-of-control murderous doings as he longs for the daughter he never got to know; and "Not While I'm Around," a loving ballad between Mrs. Lovett and Toby that takes an evil turn after the boy comes upon their maniacal scheme and can no longer be trusted to keep their secret. The blocking of all the musical scenes is coherent, lively and first-rate, while the cinematography by Dariusz Wolski (2005's "Hide and Seek") is forebodingly picturesque, the ashen surroundings boldly contrasting with the generous flow of bright-red blood in the second half.

Performances are spot-on, with perhaps one reservation. Johnny Depp (2007's "The Pirates of the Caribbean: At World's End"), at last free from the confines of Captain Jack Sparrow, relishes portraying yet another figure who, if he isn't already, is destined for iconic status. Emotionally destroyed inside and hungrily ready for revenge, Depp flawlessly encapsulates Sweeney as a man who starts killing as a means of relieving his heartache before driving over the deep end. Only Depp's acting in the last scene is a miscalculation; it demands high emotions, but Depp plays his reaction to a key discovery with too much reserve for it to have the effect it should.

As Mrs. Lovett, coconspirator to Sweeney's crimes and wannabe love interest, Helena Bonham Carter (2007's "Harry Potter and the Order of the Phoenix") is the true standout of the piece. While she could be accused of getting the part through biased casting—she is Tim Burton's girlfriend, after all—those suspicions are immediately discounted the second she pops onto the screen. Carter makes the role her own, adding shades of sympathetic depth and longing to her character as she falls in love with a man who will never love her back. Depp and Carter, both of them non-professional singers, have terrific voices well-suited to Sondheim's music. The same goes for a trio of newcomer—Edward Sanders, an endearing, headstrong find as Toby; Jamie Campbell Bower, as Anthony, whose performance of "Johanna" is beautifully carried off; and Jayne Wisener, demure and lovely (and a dead-ringer for Christina Ricci in 1999's "Sleepy Hollow") as Johanna. Finally, Sacha Baron Cohen (2006's "Borat") steals his few unforgettable scenes as the ill-fated Signor Adolfo Pirelli, his memory long remembered after he is dispatched.

Up until the very ending, "Sweeney Todd: The Demon Barber of Fleet Street" invigoratingly stood as the finest motion picture musical since 2001's "Moulin Rouge." The last scene, however, is an anticlimactic disappointment—the one flaw in an otherwise speckless production. Whereas the Broadway show concluded with "The Ballad of Sweeney Todd," this song has been taken out here, shedding the climax of a satisfactory denouement and leaving the wrap-ups of three characters—Toby, Anthony and Johanna—dangling and unfinished. Because of this, they come off more as plot constructs than formidable participants in the story, and the abrupt switch to the end credits leaves one feeling like something is missing in translation. Nevertheless, this only puts a temporary damper on what could be, and deserves to be, a modern classic. Thrilling, ghastly, goosebump-inducing and oddly romantic, "Sweeney Todd: The Demon Barber of Fleet Street" is an unqualified genre-buster, not quite like any other horror movie or cinematic musical in memory.