Shave-bonced pop diva and noted astrophysicist Yazz once declaimed "the only way is up".

Well, the route vehemently insisted on by the singing scientific theorist is pooh-poohed in this adventure yarn.

Whereas previous sci-fi blockbusters were happy to take us into space, this one burrows in between tectonic plates to the earth's core.

Apparently, the molten outer shell swirling around a solid centre of trillions of tons of nickel and iron has stopped rotating.

This means the planet's electromagnetic field, which shields the earth from deadly solar radiation, is on the blink.

"How could this have happened?" asks a Pentagon bigwig in possibly one of the most redundant rhetorical questions in cinematic history.

The tangible consequences are soon pretty clear - Trafalgar Square's pigeons lose their sense of direction and Rome's Colosseum tumbles down in an electrical storm.

However, help is at hand. A motley crew of "terranauts" is put together to drill down to the core in a vehicle known to fans of Thunderbirds as "the mole".

Steering the revolutionary contraption is Major Rebecca Childs (Swank), a Nasa navigator who managed to land an off-course space shuttle in a LA drainage channel.

Leader of the team is, er, crack geophysicist Josh Keyes (Eckhart), a super-boffin who has difficulty knotting his tie, but a winning glint in his eye.

Providing the tension is vain consultant scientist Dr Conrad Zimsky (Tucci), who dishes out thick slices of ham when he's not spitting bile.

It's a real international effort with even the French, in the form of Dr Sergei Leveque (Tcheky Karyo), deigning to make the trip (good to have them aboard).

It's simple - once they have steered a couple of thousand miles below the surface and jump-started the core with an N-bomb, they just bob back up to the top.

Rarely has hokum been so shameless and it's a tribute to director Jon Amiel that an enterprise built on such a doolally premise rolls along so entertainingly.

It's utterly mindless but made alluring by a nice wry line in self-deprecation and special effects that suggest mind-altering substances.

Dig deep into your pockets and drop in on The Core.

Tim Evans