A dark scan of the near future

As one might expect from a movie based on a novel by the late Philip K. Dick, "A Scanner Darkly" is highly unsettling. Dick has been adapted before, most notably in "Blade Runner," but this film, which was shot as live action on video and then painted over – one frame at a time – in a process called rotoscoping, is probably the most faithful to the writer's tortured spirit. It's the kind of movie that gets under your skin – and stays there.

Director Richard Linklater employed a somewhat less advanced rotoscoping technique for his "Waking Life," a more free-form and dreamlike experience. In "A Scanner Darkly," the dreaminess is less lyrical and a lot scarier. (Lest anyone think rotoscoping is a way to cheat the animation process, bear in mind that it took up to 500 hours to make each minute of "A Scanner Darkly" with 30 people working full time every day.)

Set in Orange County, Calif., seven years in the future, the film opens with a junkie frantically trying to wipe bugs (which may not be real) off his body. He's one of four dopers living in a tract home owned by Robert Arctor (Keanu Reeves), an undercover narcotics agent turned addict. They're all strung out on Substance D, which splits the user's brain into two separately operating hemispheres.

Their rampant (and often justifiable) paranoia takes many forms, as doublecrosses and deceit pile up and Arctor runs a surveillance on his own home. In effect, this means he is carrying out surveillance on himself. His split consciousness deposits him in a dark limbo where privacy no longer exists and your worst enemy may turn out to be yourself.

Dick's 1977 book – which was recently transformed into a graphic novel in collaboration with Harvey Pekar – has its prescient connections to today's political landscape, particularly when it bears down on issues of unlawful surveillance and the "culture of addiction." But I'm glad Linklater doesn't push these points – Dick's mindscape is far too indrawn and idiosyncratic for that. I'm also glad that Linklater doesn't unduly futurize this world. Compared with today, everything that we see is only slightly off kilter.

It may seem odd in this context to talk about performances, but the actors, rotoscoped though they may be, are phenomenal. After serving time in the "Matrix" movies, Reeves is hardly a stranger in this strange land; his slacker growl has never seemed more subversive. Robert Downey Jr., no stranger to these waters, either, gives his thin-skinned junkie a prickly vigilance. Woody Harrelson, Winona Ryder, and Rory Cochrane are so good that, as is also true of the other cast members, you soon forget you are watching animation. So it is with the entire movie. Grade: A–

• Rated R for drug and sexual content, language, and a brief violent image.