After the irretrievably miserable experience that was the “”Matrix”” sequels, audiences weren’t up for another romp down the rabbit hole with a pill-popping Keanu Reeves (“”The Lake House”” couldn’t have helped either). But this time, he didn’t take the blue pill. He took red ones – and lots of them.

Keanu and his fellow vacationers from reality – a whacked-out Woody Harrelson, Robert Downey Jr. as a psychophrenic conspirator and Rory Cochrane (Lucas from “”Empire Records””), two skips past a nervous breakdown – take so many “”death”” pills (Substance D) that they soon kill every brain cell they ever had.

When not hiding from The Man or scoring another hit, the laughable yet unnerving cast of characters is constantly engaged in sprawling philosophical tangents, wild paranoid delusions and raging debates about how many gears belong on an 18-speed bike: “”Three in the front and six in the back, make nine gears … where the hell are the other nine?!””

The hallucinogenic frenzy that author Philip K. Dick created in the drug-induced world of his novel comes to swirling fruition in writer/director Richard Linklater’s adaptation. He applies a patented, computer-assisted rotoscoping technique to throw an animated haze over every frame of live action, dipping his audience head-first into a surreal landscape of mania, delusion and deceit. The wavering outlines and ever-shifting colors translate a sense of confusion and instability that makes bringing your own reality suppressant unnecessary.

Don’t let thematic similarities between “”A Scanner Darkly”” and “”The Matrix”” turn you off – they are completely different films. Keanu may never again be that lovable stoner from “”Bill and Ted’s,”” and won’t win any Oscars until he learns to dodge shitty scripts the way he dodges bullets (OK, he’ll never win an Oscar), but “”A Scanner Darkly”” is a rewarding move in the right direction.