Rowdy and a bit ragged but wholly entertaining, Mat Whitecross' "Sex & Drugs & Rock & Roll" is a biopic of British punk rocker Ian Dury with a sensational lead performance by Andy Serkis, best known as Gollum from the "Lord of the Rings" films.

Set around performances by Dury and his band the Blockheads at the Watford Palace Theatre, the film takes a surrealist path to relating the rocker's journey from polio-stricken kid to top-of-the-charts entertainer.

It's an energetic and vivacious film that will appeal to fans of punk rock worldwide and should find its place in the pantheon of great music-film biographies. First-time director Whitecross and Serkis should be in line for awards.

Serkis does the singing with the real Blockhead musicians including guitarist and co-writer Chaz Jankel, portrayed winningly by Tom Hughes. Numbers given full screen time include the title track, "Billaricay Dickie," "Hit Me With Your Rhythm Stick," the controversial "Spasticus Autisticus" and the mournful tribute "Sweet Gene Vincent."

Dury never claimed to have a great voice, though it was very distinctive, and Serkis captures it perfectly. He also does a great job portraying the determinedly independent and outrageous performer's flamboyant manner.

Paul Viragh's screenplay has Dury talking onstage about his lonely upbringing with a father (Ray Winstone) who frequently was absent, leaving him at an institution for handicapped children in the care of an unfeeling orderly (Toby Jones).

The story follows Dury from his first failed band to 1970s success after hooking up with Jankel, and his love affairs with tolerant wife Betty (Olivia Williams) and young girlfriend Denise (Namoie Harris).

The two actresses contribute excellent support, and there's fine work, too, by Bill Milner ("Son of Rambow") as Dury's son Baxter, a young man whose exposure to his father's excessive rock 'n' roll lifestyle looks as it could take him off the rails.

The film is fast-paced and funny, with many jump-cuts and bits of animation, but there are scenes of great poignancy conveying Dury and his tortured relationships. The English music hall was in Dury's blood and combined with his great determination to kill off any hint of self-pity. Serkis shows as much skill in the quiet moments as he does in the splashy numbers.

"Sex & Drugs" features lots of cheerful English swearing, and the film's exuberant pleasure in depicting Dury's waywardness might put off straight-laced audiences, but punk rockers everywhere will eat it up.