Ken Livingstone's £5 congestion charge seems like a wise move after we get a glance at what lurks in London's subterranean Tube tunnels after the gates have shut.

Run Lola Run star Potente is Kate, a chic metropolitan fashionista with a taste for class A drugs and alarming polka dot cocktail dresses.

After leaving a party after one too many vodkas, she finds herself sharing an empty Tube train carriage with lecherous cokehead Guy (Jeremy Sheffield).

When he viciously pins her down. Kate is expecting the worst... until the would-be rapist is dragged off into the darkness by something Kate can't see.

Hurtling for help down the deserted corridors linking the tube lines, she comes across homeless crack addict Jimmy (Paul Rattray) and his girlfriend Mandy (Kelly Scott).

He agrees (after trousering £50) to lead her to the station control room... but someone's already got to the security supervisor (Morgan Jones) with a big knife.

This rattles along familiar lines with the added advantage of locating itself in a natural setting for the fainthearted - London's 400 miles of underground railways.

Dr Who's arch enemies - the Yeti - haunted the dripping Victorian tunnels and one of the most memorable scenes in An American Werewolf in London was shot down there.

Debut writer/director Christopher Smith uses the crumbling brick passages and soot-encrusted galleries to chilling effect (parts of the movie were shot in the disused Aldwych station).

Funnily enough, London Underground were quite happy to give him permission to film only to get all uppity when the film's posters began apeearing in the city's Tube stations.

Potente happily maintains the look of the scared witless but it's just a shame Smith opts for revealing the scaly stalker rather than keep him in the shadows.

With more jolts than the Northern Line, at least it'll make sure you never miss the last train home.

Tim Evans