The tug-of-war between altruism and materialism is at the heart of Iron Man, Jon Favreau's marvellous nuts and bolts realisation of the red and gold armoured Marvel Comics superhero, writes Damon Smith. Following the lead of the Spider-Man and X-Men franchises, Favreau devotes the majority of the opening hour to the characters. He fleshes out their personalities, insecurities and the underlying tensions (attraction, jealousy, irritation) which light the fuse on an action-oriented second half, awash with spectacular visual effects.

The central role of a billionaire industrialist, whose conscience is pricked after a brush with death, fits Robert Downey Jr like a titanium-plated glove. He's charming and roguish yet reckless with other people's emotions, and he galvanizes a sizzling screen chemistry with Gwyneth Paltrow as the personal assistant who barely flutters an eyelash at the endlessly array of one-night stands who parade through her employer's cliff-side mansion.

Brilliant inventor and consummate playboy Tony Stark (Downey Jr) is held hostage in Afghanistan by insurgents under the command of Raza (Faran Tahir), who demands that he builds a devastating Jericho missile for use against US forces. Instead, Tony and fellow prisoner of war Yinsen (Shaun Toub) use the time in captivity to fashion an ultra-strong suit of armour and orchestrate a daring escape.

Found wandering the desert by his good friend, Lieutenant Colonel James 'Rhodey' Rhodes (Terrence Howard), Tony returns to America a changed man. "I saw young Americans killed by the very weapons I created to protect them," he tells a crowded press conference. He then announces the immediate shutdown of the weapons manufacturing arm of Stark Industries, to the shock and surprise of right-hand man Obadiah Stane (Jeff Bridges). Unfortunately, members of the board freeze out Tony and soon he is fighting for control of his own company, aided by his feisty assistant, Virginia "Pepper" Potts (Paltrow).

Iron Man is terrifically entertaining, fuelled by Favreau's kinetic direction, strong performances and some thrilling action sequences. Downey Jr relishes the comic asides of his character before the transformation into his eponymous alter ego.

Repartee with Paltrow promises plenty of laughs. Bridges adds plenty of bombast but Howard is almost surplus to requirements. Potential for a bigger role in the sequel is made explicit when Rhodey stares at a spare Iron Man suit and sighs: "Maybe next time."