Tideland (15)

The melodrama of Terry Gilliam's career - his maverick reputation, conflicts with producers, the demise of his beloved Quixote project - has always threatened to overshadow the work itself. But, in 30 years, he has pursued a theme concerning the precarious interplay between reality, fantasy and psychosis which is remarkably consistent.

This is the subject of his latest, perhaps quintessential film. One could argue that Tideland doesn't work, that it is over-long and poorly paced, featuring passages of tedium and questionable taste; equally, that it confirms the adopted Brit as our most visionary contemporary film-maker.

Based on the novel by Mitch Cullin, it charts the experiences of 11-year-old Jeliza-Rose (Jodelle Ferland), a lonely girl forced by the failings of her parents to rely on her own, invented world. This is a girl desperate for love and normalcy; instead, her human contact limited to grotesques, she spirals slowly towards mental collapse.

The film opens with the tail end of her family life, the daily highlight of which involves helping her junkie parents to shoot up. Jennifer Tilly, no stranger to shrill overacting, and a grizzled, almost unrecognisable Jeff Bridges seem to be on loan from Gilliam's Fear and Loathing in Las Vegas - self-indulgent, barely audible addicts segueing from one drug-induced haze to another. As the parents from Hell, they are horribly brilliant.

When the mother overdoses, Pop, an over-the-hill rock star, takes his daughter cross-country to his late mother's dilapidated house in Texas. Soon he too is dead, residing behind his shades in the armchair, the girl continuing to cuddle up to the corpse in a sad refusal to accept her isolation.

Henceforth, Jeliza-Rose is a child cut dangerously adrift, roaming the empty landscape with companions either imaginary - talking squirrels, her bodiless Barbie heads - or unhinged. There is no way that the eccentric Dell (Janet McTeer), rampaging across the fields like a Wicked Witch of the West, and Dickens, her mentally impaired brother who dallies amorously with the girl, can do anything but harm.

Tideland can be viewed alongside Gilliam's The Fisher King, in particular: in each, a loner seeks refuge in imagination, only to teeter on the edge of madness. What makes this film infinitely more disturbing is that this is a child in the hands of unreliable adults; Gilliam's uncommon restraint in handling the intimations of paedophilia, by the way, makes it all the harder to watch.

The director has described this as Alice in Wonderland meets Psycho. It's not as enjoyable or compelling as either - indeed, it is alternately boring and bonkers. Yet the description does fit its baroque imagining of a waking nightmare. And who ever said nightmares are fun?