"A Scanner Darkly" is the second film from writer-director Richard Linklater that has adopted rotoscoping animation to tell its story (following 2001's pretentious attempt at existentialism, "Waking Life"). A time-intensive process in which the film is shot like any live-action project would be, only for the actors and their surroundings to be traced over and colored in during post-production, rotoscoping lends the images a surreal, dreamlike quality that one cannot quite capture any other way. For "A Scanner Darkly," the technique is essential to telling the story; without it, the picture would be terminally dull, forgettable, and unworthy of a cinematic berth.

The place is Los Angeles. The time is "seven years from now." And the illegal, mind-altering drug of choice is Substance D, or simply Death, a potent hallucinogen with brain damage being an unfortunate side effect. By day, Bob Arctor (Keanu Reeves) is Fred, an undercover police agent who hides his identity through the wearing of a Scramble Suit and has begun a secret surveillance on buddies James Barris (Robert Downey Jr.) and Eric Luckman (Woody Harrelson). By night, Bob Arctor (Keanu Reeves) is a one-time family man who has abandoned his wife and child and now lives with James and Eric in a drug-induced haze, an addict of the very drugs he tries to stop in his work. Also figuring into Bob's life is girlfriend Donna Hawthorne (Winona Ryder), a drug dealer whose use of narcotics is making it less easy for him to quit. As the recorded spying intensifies and the lines between reality and hallucinations blur, Bob's superior at the police station moves closer to the true identity of Fred.

Adapted from the novel by famed late science-fiction writer Philip K. Dick, "A Scanner Darkly" is another example of a motion picture that has been mismarketed in its trailers and other advertising. This time the culprit isn't a comedy more serious than lighthearted (i.e. "The Break-Up," "Click," "You, Me and Dupree"), but a suspense-laden thriller that isn't laden with suspense or particularly thrilling. It doesn't test one's patience quite like "Waking Life" did, nor is it as inaccessible in dialogue and subject matter, but there are similarities. Both are less concerned with plot than in evoking a heavy mood and off-kilter tone through the use of the dynamic rotoscoping animation. Both resist the urge to fall underneath the average tastes of mainstream viewers, their complex material and unorthodox paths to a less-than-happy ending sure to perplex a fair share of moviegoers. Both are more talky than action-oriented, with an onslaught of scenes where characters just sit around and carry on conversations—most often while being high as a kite and making as much sense as a Mad Hatter. That latter detail is one of the biggest problems with "A Scanner Darkly," because the incoherence of the drugged-out characters' wordplay comes off sounding plainly idiotic and irritating for the sober audience member. In my experiences, it's no fun being around drunk people when you yourself aren't drinking, and the same kind of applies here when dealing with these people and their asinine back-and-forth.

The performances are tricky to gauge, not because the actors' bodies have been animated over, but because their characters are unappealing. Leads Keanu Reeves (2006's "The Lake House") and Winona Ryder (2002's "Mr. Deeds") fare the best because they underplay rather than blow up into exaggerations. As Bob/Fred, Reeves commits to the role with an intensity in his eyes, but his work is marginalized by a screenplay from Richard Linklater that washes over his background as a deadbeat dad and doesn't portray him physically taking drugs nearly enough to plausibly believe he is as zonked-out as inferred. In her first major film appearance in four years, Ryder makes a cordial return to form as Donna, who is torn between her want for intimacy with Bob and her unwillingness to kick the habit. When Donna's part takes some sudden turns near the finale and deepens as a result, so does Ryder's well-modulated performance. The supporting players get in the way. Robert Downey Jr. (2006's "The Shaggy Dog"), Woody Harrelson (2006's "A Prairie Home Companion") and Rory Cochrane (2002's "Hart's War") have the speech, body language and paranoia down pat as three under-the-influence druggies, but their overly excitable appearances wear thin fast. Harrelson and Cochrane are especially superfluous, their only apparent purpose to italicize the message that "drugs are bad."

Visually, "A Scanner Darkly" is a vivid achievement. The effect of the Scramble Suit, a cloth covering with a million different people's physical features put into a garbled loop, is brilliantly achieved because, when one knows who the wearer is, they can still be glimpsed behind the rest of the countless disguising faces. Additionally, the movements of the people and objects and backgrounds (the driving scenes deserve special mention) have a lifelike fluidity that jump off the screen and reassure this is no ordinary animated film. In fact, individual shots look eerily identical to live-action, while others are like snapshots from an alternate reality where everything is just a little too abstract for comfort.

Unfortunately, as imaginative and eclectic as its aesthetic sheen is, "A Scanner Darkly" is emotionally stolid and, in the final scenes, so preachy in its anti-drug stance that it might as well have had the financial support of D.A.R.E. during its production. There is nothing wrong with the subject matter writer-director Richard Linklater touches upon—he also makes fleeting comments about the government's gnarled love-hate relationship to drug manufacturers and the topical debate for and against private surveillance—but he tends to either sermonize his points or avoid digging deep enough to say something interesting or provocative. The end of "A Scanner Darkly" leads to one question: is that all there is? In the simplest terms, the film never takes off or involves the viewer beyond its quirkily animated outer shell.