Dirty Harry in outer space?

A lanky man in a blue suit stalks a caped villain through a shadowy web of girders in the broadcast tower that dominates Alba City on Mars. The costumed marchers and jack-o-lantern balloons in the Halloween parade on the street below provide an innocent yet ominous backdrop to the deadly game of cat-and-mouse.

The villain Vincent plans to infect everyone in Alba with deadly nano-machines, microscopic robots made of protein, undetectable to medical science. The ISSP (Inter Solar System Police) and the army have mistakenly staked out the water treatment plant. Only Spike Spiegel and his partners can save the human population of Mars.

We’re in the animated world of “Cowboy Bebop: The Movie: Knockin’ on Heaven’s Door,” which opens Friday in limited release in Los Angeles and other U.S. cities. It continues the interplay of stylish noir adventure and sardonic humor that made the “Cowboy Bebop” television series so popular in Japan and America. It’s been running on the Cartoon Network as part of the “Adult Swim” block since September 2000. VideoScan ranks it as the bestselling DVD anime series in North America. Although 21st century bounty hunter Spike Spiegel is described as a “space cowboy,” he’s a laconic antihero in the tradition of the noir detectives of the ‘40s. “Knockin’ on Heaven’s Door” is a striking example of the ongoing cross-pollination between American live action and Japanese animation. The R-rated film (for some violent images), which is being released by Destination Films and IDP Distribution, is aimed at an adult audience -- particularly young males.

Director Shinichiro Watanabe, who says he “grew up on American movies,” talked about the film recently in a telephone interview from his home in Tokyo. Speaking through an interpreter, Watanabe explains that “I was influenced by American movies of the ‘60s and ‘70s, especially Don Siegel’s ‘Dirty Harry’ and the films of Sam Peckinpah. And, of course, a lot of the film noir movies of the ‘40s.”

Spike is a tough guy in a tough racket. He’s a crack shot, an ace pilot and a skilled martial artist, but beneath his cynical exterior is a wound that’s never healed, left by the woman he loved and lost. Watanabe comments, “Some people compare Spike Spiegel to Dirty Harry, and they’re both antiheroes.

“But Spike is an extension of myself. I don’t smoke or drink or fight, but I want to -- so Spike does.”

Steven Jay Blum, who provides the English voice for Spike in the movie and the series, says, “Live-action noir detective films definitely help me: I mentally tip the fedora and get the cigarette in my mouth, and it helps me lock into the character, especially in moments that are uncomfortable for me. The most uncomfortable sequences for Spike are when he is vulnerable, like the scene in jail when he [talks about] how he came to fear death. It’s hard for me to go to that place in life, and it takes some help for me to get there in the studio.”

Mean, jazzy streets

The closest thing Spike has to a friend is his partner, Jet Black, the owner, captain and cook of the spaceship Bebop. A former ISSP officer with a robotic left arm and a scarred face, Jet tries to keep a rein on Spike, whom he describes as “all instinct and impulse.” In the first episodes of the series, they were joined -- against their wishes -- by the rest of the regular cast: Faye Valentine, a voluptuous unsuccessful gambler; adolescent hacker Edward Wong (a girl, despite the name); and Ein, a “data dog” that resembles a Welsh corgi. They’re all perennially broke and hope to find a criminal with a large bounty on his head.

Spike and his cohorts travel down grimy streets in two-bit towns and casino-satellites. Watanabe explains, “I wanted to create a futuristic world, but a world that people actually live in. Only movie characters could live in the worlds they depict in ‘Star Wars’ and other science-fiction films. I wanted to make a world where people live and breathe. Even if it’s just a shot of an empty sidewalk, there should be cigarette butts or some other visible traces that people actually walk through that setting.”

The noir tone is intensified by Yoko Kanno’s jazz-inflected score. Few big-budget Hollywood features have suggested urban alienation as effectively as this brooding marriage of gritty cityscapes and melancholy saxophone riffs.

A highly respected composer in Japan, Kanno has written scores for some of the best anime features and series of recent years, including “Ghost in the Shell,” “Cardcaptor Sakura” and “Jin-Roh: The Wolf Brigade.” Watanabe describes their collaboration as an enthusiastic give-and-take, with each artist striving to match the other’s vision.

A nod to Peckinpah

The influence of Sam Peckinpah can be seen in the dynamic choreography and camerawork in the climactic hand-to-hand combat between Spike and Vincent on the broadcast tower. Spike gets thrashed, but according to Blum, creating the illusion of getting punched is “just a vocal trick. Sometimes I’ll punch myself or I’ll throw a kick -- whatever I need to do to get the sound as accurate as possible. But I have to stay centered on the mike at all times, so I really can’t move around.”

“Knockin’ on Heaven’s Door” is likely to satisfy fans of the TV series: The final episode left them with the same sense of loss many people felt when the first “Star Wars” trilogy ended. But the film deserves a wider audience. For years, American animators have wanted to make a feature that captured the dark expressionism of noir detective movies. Watanabe shows how it can be done -- if the studio is willing to accept an R rating for an animated film.

Since completing “Knockin’ on Heaven’s Door,” Watanabe has directed two segments of “Animatrix,” the American-Japanese co-production scheduled for video release in June in conjunction with the “Matrix” sequels. He’s currently at work on a samurai adventure series for TV.

Although there are no plans for further installments of “Cowboy Bebop” at this time, Watanabe concedes that Spike’s adventures “will probably continue at some time in the future, although I’m not sure in what form. When the original 26-episode series concluded, a lot of fans and sponsors wanted me to continue. That’s why I made this movie.”