It's the one thing any Hollywood high-roller worth their artistic salt cannot resist - the total physical transformation to play a social misfit.

Dustin Hoffman embraced autism for Rainman while Daniel Day-Lewis and Tom Cruise clambered into wheelchairs for My Left Foot and Born on the 4th of July.

Now ex-model and ballerina Charlize Theron - who was last seen looking decorous in the glossy remake of The Italian Job - has stepped into the shoes of a serial killer.

Homeless hooker Aileen Wuornos confessed to the murder of six "johns" while working the highways of Florida, claiming she was acting in self-defence.

Theron piled twenty-five pounds onto her lithe frame, spat out Wuornos' bitter words through a set of false dentures and underwent hours of makeup to nail the role.

However, it's her visceral performance that takes the breath away - Theron captures every explosive rant and desperate, head-tossing challenge to perfection.

Anyone who has seen British documentary-maker Nick Broomfield's two films featuring Wuornos will be astounded how comprehensively Theron inhabits this pulsing bundle of nervous and ultimately violent energy.

First time director Patty Jenkins - who corresponded with Wuornos while on death row - relates how she killed to fuel her romance with lesbian tease Selby Wall (Ricci).

This is where the film falters: the implausibly young-looking Ricci appears miscast in an underwritten role that doesn't stand up to scrutiny.

However, it's Theron's Oscar-winning performance that will stay in the memory as she despatches a series of sordid men to underwrite her doomed relationship with the needy Wall.

Rather than sympathy, the apparently ego-less Theron achieves a level of empathy as the increasingly desperate Wuornos can only mouth empty bravado as events spiral out of control.

It would be interesting to hear what Wuornos herself made of her portrayal - but she was executed on October 9 2002.

"You'll never meet someone like me again," Wuornos tells her lover. And for that we can only be thankful.

Tim Evans