Superheroes are usually equipped with all manner of impressive powers - from the ability to fly, scale skyscrapers with a sticky web to having superhuman strength.

Iron Man, based on the Marvel Comics story, is different in that he's an ordinary guy in a very powerful suit.

Robert Downey Junior plays billionaire playboy Tony Stark who is a technical genius and arms manufacturer under sole contract to the US military.

While in Afghanistan, Stark's convoy comes under attack and he is taken prisoner.

When he comes round in a cave he discovers a doctor has fitted an electro-magnetic ring in his chest to stop shrapnel travelling into his heart and killing him.

His menacing captors demand he builds them a hi-tech bomb but Stark secretly creates an iron flying suit and manages to escape captivity.

Back on US soil he uncovers an evil plot with global implications - involving someone inside his own firm.

So with the help of his ridiculously named but loyal assistant, Pepper Potts (played by Gwyneth Paltrow), Stark dons his powerful armour and vows to protect the world as Iron Man.

Downey Junior is likeable as both the amoral Stark and the do-gooder Iron Man. There's some enjoyable dead-pan humour and slapstick in Stark's quest to perfect his suit and his chemistry with the under-used Paltrow adds a human dimension to the rather technical proceedings.

Jeff Bridges, as usual, is excellent as Stark's ruthless business partner Obadiah Stane.

Actor turned director Jon Favreau has made an extremely watchable movie jam-packed with stunning special effects and thrilling hi-tech wizardry - but it is a little overlong and there are some lapses in logic.

Iron Man might not win any awards any time soon but it is fun with a capital F.

This is one franchise which could really take off - so why not fasten your seat belt and enjoy the ride?