Slumdog Millionaire (15)
Star rating: *****
Dir: Danny Boyle
With: Dev Patel, Anil Kapoor, Irrfan Khan, Freida Pinto

Cometh the most depressing month in what we are promised will be a dismal year, cometh Slumdog Millionaire, a picture so brimful of cheer it makes you want to punch the air rather than the nearest banker. So uplifting is Danny Boyle's picture one feels obliged to check the credits for Gordon Brown's name, just to see he hasn't commissioned it especially for these testing times.

Hang on a mo', however. Before the good times can roll there's a opening scene of torture to be endured. The British director of Shallow Grave and Trainspotting might have made one of the most genuinely crowd-pleasing and visually sumptuous dramas of recent years, but he still likes to do things his own, gritty way.

With a screenplay by Simon Beaufoy - writer of The Full Monty - that means exploring the badlands of modern-day Mumbai, not tiptoeing through fields of tulips. In this town, the old ways of police brutality rub up against the new drive for riches and western glamour, with little people like Jamal (Dev Patel) the hapless torture victim, caught in the middle.

Jamal used to be one of the slumdogs of the title, an orphaned boy who grew up on the streets. Tough as it has been, he's managed to haul himself up to working as a teaboy in a call centre. What brings him to the attention of police are his appearances on Who Wants to Be a Millionaire?, the Indian version of which is exactly like the British quiz show, right down to its cheesy host (played by Anil Kapoor). Jamal is proving so successful on the programme he is suspected of cheating. He, how-ever, puts his good fortune down to the simple fact that he knows the answers. But how can a slumdog with no schooling be a top dog in general knowledge?

The answers, it turns out, are to be found buried in Jamal's past. Through a series of flashbacks, Boyle and Beaufoy, who based the screenplay on Vikas Swarup's novel Q&A, match the questions being asked in the Millionaire studio to incidents and people in Jamal's childhood. He knows about a certain song, for instance, because he heard it during his orphanage days.

This trail-of-breadcrumbs approach, a clever if thoroughly old-fashioned device, allows Boyle to journey between the making of Jamal and the predicament he finds himself in today. Ever the orphan, Jamal has lost touch with the people who once meant the world to him. Tracing a long-gone first love and an estranged sibling won't be as easy as naming songs or identifying movie stars, but our hero is determined to try for the jackpot on those scores too.

Boyle captures the episodes from Jamal's past with his trademark flair. The director of Sunshine has an eye for the gruesome as well as the sublime, and both are put to memorable use here. There is one scene, involving a tiny boy and a toilet, that would call to mind Trainspotting if you weren't too busy gasping and laughing at the sheer audacity of it all. Being Boyle, it also gives you a chase scene helter-skelter enough to make your nose bleed.

The backdrop to the melodrama is Mumbai, intimate and sprawling, dilapidated and gorgeous, its shiny new skyscrapers poking their fingers through the mass of slums and toiling humans below. The tumble of colours, from the morning sky to the fresh produce in the street markets, is amazing. Never mind Gordon Brown in the credits; Mumbai should be given a character listing all its own.

Although there's a dreamy, fantastical, Bollywood air to Slumdog Millionaire, Boyle is keen to inject some reality checks along the way. Staff at a call centre are seen being briefed on the latest British soap plots and what they should drop into the conversation if the caller is, say, from Scotland (whisky, Sean Connery and Ben Nevis, since you ask). Jamal's home city might still, at a push, be deemed part of the developing world, but it is catching up at warp speed.

As we inch nearer to finding out whether Jamal makes it all the way through the quiz, the lines of the story converge. From this point on you'll need a very sweet tooth and a wide open mind.

Some might find there's also a tad too much of the quiz itself, making the film seem at times like one lengthy advert for Who Wants to Be a Millionaire? But I was more than happy to be swept along by the story. Slumdog Millionaire is a movie you don't want to look at too closely for fear the magic will turn to dust.

Boyle has gone old-school with a picture that aims to gladden the heart, pure and simple. With more films like this we'd all be millionaires - in spirit if not in cold, hard cash.