Dir, Scr: Richard Linklater. USA 2006. 100 mins.

Returning to the animated live-action technique of his 2001 philosophical doodle Waking Life, the hyper-productive Richard Linklater has come up with what must surely be the first sci-fi slacker movie.

Based on Philip K Dick's cult novel of the same name, this is an entertainingly oddball ride, though also a meandering one. But when the conspiratorial surveillance plot gets too confusing we can fall back on the surreal wit of the dialogue and the sheer visual richness of the exercise, which comes on like an animated acid trip.

With a high-octane cast led by Keanu Reeves, A Scanner Darkly is a far more commercial prospect than Waking Life, but still a niche product: urban irony and subculture sympathies are key audience requirements. Reams of fast-paced dialogue could make subtitling a headache in territories where dubbing is not the norm.

Set in Orange County, California, A Scanner Darkly posits a near future where twenty per cent of the population is addicted to an illegal drug called Substance D. The US army has occupied countries that supply the drug while at home the Substance D plague is used by the government as a licence to harangue, control and spy on just about everybody. A sinister corp, New Path, has a monopoly on the state-sponsored rehab programme.

Keanu Reeves plays Bob Arctor, a D-user who lives with his odd friends in a shabby 1960s-modernist suburban house. But Bob has another life, and identity, as Fred, an undercover policeman. Fred's identity is kept secret by the 'scramble suit' all undercover cops are required to wear, which turns features and clothes into a never- ending morph of thousands of faces and costumes. One of the most striking images created by the 30-man animation team, the scramble suit is an uneasy, unstable Everyman, melting before our eyes like an animated Francis Bacon portrait.

The dysfunctional surrogate family that Bob shares his house with includes twitchy motor-mouthed geek Jim Barris (Robert Downey Jr) and degraded surfer dude Ernie Luckman (Woody Harrelson); whacked-out addict Freck (Rory Cochrane) and Bob's edgy drug-dealing girlfriend Donna (Winona Ryder) also orbit the dishevelled nest.

The main plot kicks in when Bob is asked to spy on his own household by his superior, but the drugs are messing with his synapses and he soon finds it difficult to distinguish between his paranoid fantasies and reality.

Reeves does a decent job of the lead role, playing Bob as a more addled version of Neo from the Matrix trilogy, but the standout performance is Robert Downey Junior's hugely enjoyable take on Jim Barris. Barris at first seems to be one of the sanest of the bunch, but his querulous and long-winded attempts to explain things turn out to be just as cracked as his fellow addicts' more obvious psychoses, and he is at the centre of some of the film's most hilarious scenes - such as the one involving a possibly stolen mountain bike. There's also fun to be had in watching such well-known faces act beneath those cartoon masks: it's a compelling and faintly unsettling experience.

The animation uses the same technique of digital treatment of live-action photography as in Waking Life - a process known as interpolated rotoscoping. There is plenty of scope for individual manipulation of images across a range of looks, from 'flat' animation to a lush painterly style; sometimes two or more styles coexist within the same frame. This gives the film a fluid, hand-painted feel: it's the Impressionist revolution breaking into the stuffy Disney and Pixar academy. The rotoscoping treatment would not work for all stories, but it's appropriate to this tale of uncertain loyalties and shifting truths.

Philip K Dick is today the most adapted modern author after Stephen King. A Scanner Darkly makes a worthy addition to the list: few of the previous decantings have come this close to the kooky, paranoid, digressive spirit of the author's work.

Production companies
Warner Independent Pictures
Thousand Words
Section Eight
Detour Filmproduction
3 Arts Entertainment

International distribution
Warner Bros

Anne Walker-McBay
Tommy Pallotta
Palmer West
Jonah Smith
Erwin Stoff

Executive producers
George Clooney
Steven Soderbergh
Jennifer Fox
Ben Cosgrove
John Sloss

Shane F Kelly

Production design
Bruce Curtis

Sandra Adair

The Golden Arm Trio

Main cast
Keanu Reeves
Robert Downey Jr
Woody Harrelson
Winona Ryder
Rory Cochrane