Directed by Bruce Sinofsky and Joe Berlinger, starring James Hetfield, Lars Ulrich, Kirk Hammett, Bob Rock, Phil Towle, Jason Newsted and Robert Trujillo.

"Anyone who says money can't buy you happiness," former Van Halen frontman David Lee Roth once opined, "doesn't know where to shop." Well, Metallica have been loaded for years but, as 'Some Kind of Monster' shows, it wasn't bringing them too much joy. They sold 90m albums and were a huge live draw, but from 1991 onwards Metallica's street cred began reducing in inverse proportion to their bank balances. Their three-year tour to promote the massive 'Black Album' featured drumkits that moved on stage and extended solos; the band wore eyeshadow on shots to accompany the 1996 album 'Load'; then came an over-the-top collaboration with the San Francisco Symphony Orchestra followed by - most damaging of all - bassist Jason Newsted quitting and the Napster debacle.

Originally conceived as a behind-the-scenes look at the making of their first proper studio album in five years, 'Some Kind of Monster' lived up to its name and mutated into a documentary about a band teetering on the brink and at each other's throats. With the pressure on to deliver a blistering comeback record, Metallica hire $40,000-a-month performance coach (ie therapist) Phil Towle to help them get "in the zone" and broaden their knowledge of similar catchphrases and each other. And from the outset it's apparent that however well Phil is paid, he's going to earn some of it the hard way. Work has barely started when singer James Hetfield enters rehab and doesn't reunite with the band for a year, sessions and songs are scrapped and the frontman's relationship with drummer Lars Ulrich deteriorates rapidly. It's the kind of scenario that would make any documentary makers hug each other with joy in quiet moments away from their subjects, but 'Some Kind of Monster' comes across as a missed opportunity.

For long-time fans, who've devoured Metallica copy over the years, Sinofsky and Berlinger's film won't tell them much about the troubled recording of the 'St Anger' record that they didn't know already - Hetfield is controlling, Ulrich has a massive ego and Hammett tries to stay out of their way. With no narration (just some onscreen titles) there's far too much footage of studio sit-downs and not enough in-depth interviews with and hard questioning of the players involved - the directors shot 1,600 hours over three years and some of it had to be more interesting than what's ended up onscreen. There are some great moments - former guitarist Dave Mustaine rounding on Ulrich, Ulrich and producer Bob Rock turning up backstage to see Newsted after his new band's show, only to find he's already gone home - but they only serve to show up how dull other parts of the film are.

What saves the documentary is the humour of seeing a huge band unable to figure out their next move and at times 'Some Kind of Monster' veers dangerously and hilariously close to 'This is Spinal Tap'. "Where does a record start?," asks Ulrich, "Where does it end?" Hammett gets upset about the absence of solos on the record, summoning up the spirit of Nigel Tufnel's classic "my solos are my trademark" quote. All you have to do is look at Bob Rock and 'Tap's leader David St Hubbins comes to mind and the scene where he gets Ulrich to scream an expletive into a mic for a new song will have anyone who swears by Metallica's early albums in hysterics. With Rock also filling in on bass, the four decide to collaborate on the lyrics - a process which brings the theory that you can democratise anything except talent into sharp focus. It's all enough to fill any teenage band encountering girlfriend/homework/bus money issues with hope that they too can achieve world domination.

By the close you're only slightly wiser as to how the situation in Metallica became so far gone. Furthermore, how could bandmates, who had experienced and achieved so much together, not feel they could just lock themselves in a room and sort out whatever problems, real or imagined, they had without having someone hold their hands? Sinofsky and Berlinger's inability to tackle those questions renders their film sometimes interesting but never essential viewing. That said, it is easier to like and admire than the album that spawned it.

Harry Guerin